QUASAR9

New Evidence of Dark Matter from Hubble?

2009-03-12T20:25:00.000Z

The Hubble images provide further evidence that the undisturbed galaxies are enshrouded by a "cushion" of dark matter, which protects them from their rough-and-tumble neighbourhood.

Dark matter can't be directly seen or isolated in a laboratory. Yet it makes up the bulk of the matter in the universe. It is the invisible scaffolding for the formation of stars and galaxies. Dark matter is not made of the same stuff that stars, planets, and people are made of. That stuff is normal "baryonic" matter, consisting of electrons, protons, and neutrons. For 80 years astronomers have known about dark matter's "ghostly" pull on normal matter. They've known that without the gravitational "glue" of dark matter galaxy clusters would fly apart, and even galaxies would have a hard time holding together.

Now the Hubble Space Telescope has uncovered a strong new line of evidence that galaxies are embedded in halos of dark matter. Peering into the tumultuous heart of the nearby Perseus galaxy cluster, Hubble's sharp view resolved a large population of small galaxies that have remained intact while larger galaxies around them are being ripped apart by the gravitational tug of other galaxies. The dwarfs' "invisible shield" is a robust halo of dark matter that keeps them intact despite a several-billion-year-long bumper-car game inside the massive galaxy cluster.

Observations by Hubble's Advanced Camera for Surveys spotted 29 dwarf elliptical galaxies in the Perseus Cluster, located 250 million light-years away and one of the closest galaxy clusters to Earth. Of those galaxies, 17 are new discoveries.

Because dark matter cannot be seen, astronomers detected its presence through indirect evidence. The most common method is by measuring the velocities of individual stars or groups of stars as they move randomly in the galaxy or as they rotate around the galaxy. The Perseus Cluster is too far away for telescopes to resolve individual stars and measure their motions. So Conselice and his team derived a new technique for uncovering dark matter in these dwarf galaxies by determining the minimum mass the dwarfs must have to protect them from being disrupted by the strong, tidal pull of gravity from larger galaxies.

Studying these small galaxies in detail was possible only because of the sharpness of Hubble's Advanced Camera for Surveys. Conselice and his team first spied the galaxies with the WIYN Telescope at Kitt Peak National Observatory outside Tucson, Ariz. Those observations, Conselice says, only hinted that many of the galaxies were smooth and therefore dark-matter dominated. "Those ground-based observations could not resolve the galaxies, so we needed Hubble imaging to nail it," he says.

The Hubble results appeared in the March 1 issue of the Monthly Notices of the Royal Astronomical Society.

Astronomer Christopher Conselice of the University of Nottingham, U.K., and leader of the Hubble observations. Other team members are Samantha J. Penny of the University of Nottingham; Sven De Rijcke of the University of Ghent in Belgium; and Enrico Held of the University of Padua in Italy.

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Trio of Galaxies mix it up

2009-03-06T08:02:00.002Z

This NASA Hubble Space Telescope image shows three galaxies playing a game of gravitational tug-of-war that may result in the eventual demise of one of them.

Located about 100 million light-years away in the constellation Piscis Austrinus (the Southern Fish), the galaxy interaction may ultimately lead to the three reforming into two larger star cities.

The three galaxies—NGC 7173 (middle left), NGC 7174 (middle right), and NGC 7176 (lower right)—are part of Hickson Compact Group 90, named after astronomer Paul Hickson, who first cataloged these small clusters of galaxies in the 1980s.

NGC 7173 and NGC 7176 appear to be smooth, normal elliptical galaxies without much gas and dust.

In stark contrast, NGC 7174 is a mangled spiral galaxy that appears as though it is being ripped apart by its close neighbors. The galaxies are experiencing a strong gravitational interaction, and as a result, a significant number of stars have been ripped away from their home galaxies. These stars are now spread out, forming a tenuous luminous component in the galaxy group.

Ultimately, astronomers believe that NGC 7174 will be shredded and only the two "normal" elliptical galaxies (NGC 7173 and NGC 7176) will remain.
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The Heart Nebula

2009-02-14T06:57:00.000Z

IC 1805: The Heart Nebula Credit & Copyright: Daniel Marquardt

Sprawling across almost 200 light-years, emission nebula IC 1805 is a mix of glowing interstellar gas and dark dust clouds. Its nickname is the Heart Nebula.

About 7,500 light-years away in the Perseus spiral arm of our galaxy, stars were born in IC 1805. In fact, near the cosmic heart's center are the massive hot stars of a newborn star cluster also known as Melotte 15, about 1.5 million years young.

A little ironically, the Heart Nebula is located in the constellation Cassiopeia. From Greek mythology, the northern constellation is named for a vain and boastful queen.

This deep view of the region around the Heart Nebula, cropped from a larger mosaic, spans about 2.5 degrees on the sky or about 5 times the diameter of the Full Moon.
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Temporary Migration

2009-02-08T20:05:00.006Z

Quasar9 is temporarily migrating to Facebook
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Snow in Cambridge

2009-02-02T23:24:00.003Z

An unusual & rare sight
Cambridge covered in a blanket of white snow
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Centaurus A

2009-02-01T12:09:00.002Z

Credit: X-ray: NASA/CXC/CfA/R.Kraft et al.; Submillimeter: MPIfR/ESO/APEX/A.Weiss et al.; Optical: ESO/WFI

This image of Centaurus A shows a spectacular new view of a supermassive black hole's power.

Jets and lobes powered by the central black hole in this nearby galaxy are shown by submillimeter data (coloured orange) from the Atacama Pathfinder Experiment (APEX) telescope in Chile and X-ray data (coloured blue) from the Chandra X-ray Observatory.

Visible light data from the Wide Field Imager on the Max-Planck/ESO 2.2 m telescope, also located in Chile, shows the dust lane in the galaxy and background stars.

The X-ray jet in the upper left extends for about 13,000 light years away from the black hole. The APEX data shows that material in the jet is travelling at about half the speed of light.
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Glass handblown

2009-01-12T19:31:00.004Z

Glassmaking was accidentally discovered by potters around 3000 B.C. and the technique of glass blowing was invented around 100 B.C.

The first glass made in North America was in Mexico in 1535 by artisans brought by the Spanish from Europe. Although these original glassworks were short lived, glassblowing was reintroduced into Mexico hundreds of years ago and flourished, due largely to the simplicity of the ingredients and the ingenuity of the Mexican arts and crafts tradition.

Today Mexico is well known for rustic handblown drinking glasses, many of them characterized by a cobalt blue band at the rim.

To create different colours, various metal oxides are added. Small amounts of iron and sulphur will achieve amber and brown effects while green and aqua glasses require iron.

Light blues need copper, while dark blues contain very small quantities of cobalt. Pastel colours can also be achieved by adding crushed glass of the desired colour.
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Blown Glass

2009-01-06T14:25:00.000Z

Blown Glass, Jerusalem, 50 BCE by Laura Duch '98

Glass is made from a mixture of sand, potash, soda, and lime or red lead. It has been called a liquid solid, because it solidifies without crystallizing. Vases and perfume bottles are some of the earliest forms of glass found by historians.

The oldest samples come from ancient Egyptian pyramids; they are usually in the form of perfume bottles. These small but ornate bottles were placed with the dead to catch the tears of their loved ones.

The discovery, in the first century BCE, that glass could be blown with a pipe seems to have been made in Palestine.
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Happy New Year

2008-12-31T22:28:00.003Z

Congrats to Xmichra ond welcome to the 'new arrival'
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The Star of Bethlehem

2008-12-24T01:00:00.000Z

The Star of Bethlehem, also called the Christmas Star, is a star in Christian tradition that revealed the birth of Jesus to the magi (or "wise men") and later led them to Bethlehem.

According to the Gospel of Matthew, the magi were men "from the east" who were inspired by the appearance of the star to travel to Jerusalem. There they met King Herod of Judea, and asked where the king of the Jews had been born. Herod then asked his advisers where a messiah could be born. They replied Bethlehem, a nearby village, and quoted a prophecy by Micah. While the magi were on their way to Bethlehem, the star appeared again. Following the star, it stopped this time above the place where Jesus was born. The magi found Jesus with his mother, paid him homage, worshipped him and gave gifts. They then returned to their "own country".

Christians generally regard the star as a miraculous sign given by God to mark the birth of the Christ (or Messiah). Some theologians claimed that the star fulfilled a prophecy, known as the Star Prophecy. In modern times, astronomers have proposed various explanations for the star. A nova, a planet, a comet, an occultation, and a conjunction (massing of planets) have all been suggested. The star has also been interpreted as an astrological event.
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Double Dumbbell

2008-12-17T19:39:00.004Z

The Dumbbells Credit & Copyright: Daniel López, IAC

These two nebulae are cataloged as M27 (left) and M76, popularly known as The Dumbbell and the Little Dumbbell. Their popular names refer to their similar, dumbbell or hourglass shapes.

Both are planetary nebulae, gaseous shrouds cast off by dying sunlike stars, and are similar in physical size, at a light-year or so across. In each panel, the images were made at the same scale, so the apparent size difference is mostly because one is closer.

Distance estimates suggest 1,200 light-years for the Dumbbell compared to 3,000 light-years or more for the Little Dumbell. These deep, narrow-band, false-colour images show some remarkably complex structures in M27 and M76, highlighting emission from hydrogen, nitrogen, and oxygen atoms within the cosmic clouds.
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Starburst Galaxy NGC 1569

2008-11-26T09:03:00.007Z

Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), and A. Aloisi (STScI/ESA)

Astronomers have long puzzled over why a small, nearby, isolated galaxy is pumping out new stars faster than any galaxy in our local neighborhood.

Now NASA's Hubble Space Telescope has helped astronomers solve the mystery of the loner starburst galaxy, called NGC 1569, by showing that it is one and a half times farther away than astronomers thought.

The extra distance places the galaxy in the middle of a group of about 10 galaxies centered on the spiral galaxy IC 342. Gravitational interactions among the group's galaxies may be compressing gas in NGC 1569 and igniting the star-birthing frenzy.

"Now the starburst activity seen in NGC 1569 makes sense, because the galaxy is probably interacting with other galaxies in the group," said the study's leader, Alessandra Aloisi of the Space Telescope Science Institute in Baltimore, Md., and the European Space Agency. "Those interactions are probably fueling the star birth."

The farther distance not only means that the galaxy is intrinsically brighter, but also that it is producing stars two times faster than first thought. The galaxy is forming stars at a rate more than 100 times higher than the rate in the Milky Way. This high star-formation rate has been almost continuous for the past 100 million years.

Discovered by William Herschel in 1788, NGC 1569 is home to three of the most massive star clusters ever discovered in the local universe. Each cluster contains more than a million stars.

"This is a prime example of the type of massive starbursts that drive the evolution of galaxies in the distant and young universe," said team member Roeland van der Marel of the Space Telescope Science Institute. "Starburst galaxies can only be studied in detail in the nearby universe, where they are much rarer. Hubble observations of our galactic neighborhood, including this study, are helping astronomers put together a complete picture of the galaxies in our local universe. Put the puzzle pieces in the right place, as for NGC 1569, and the picture makes much more sense."

Aloisi and her team actually discovered the new distance by accident. They were using Hubble's Advanced Camera for Surveys to hunt in NGC 1569 for the kind of red giant stars (stars near the ends of their lives) that shine because of fusion of helium nuclei in their cores. These stars are dimmer than bright red giants without helium burning, but when detected, they can be used to estimate the galaxy's age.

"When we found no obvious trace of them, we suspected that the galaxy was farther away than originally believed," said Aaron Grocholski of the Space Telescope Science Institute and the lead author on a paper describing the results. "We could only see the brightest red giant stars, but we were able to use these stars to recalibrate the galaxy's distance." Bright red giants are reliable "standard candles" for measuring distance because they all shine at the same brightness. Once astronomers know a star's true brightness, they can calculate its distance from Earth.

Previous estimates of the galaxy's distance made with ground-based telescopes were unreliable because they looked at the galaxy's crowded core and were unable to resolve individual red giant stars.

The Hubble study observed both the galaxy's cluttered core and its sparsely populated outer fringes. The sharpness of Hubble's Advanced Camera pinpointed individual red giants, which led to a precise distance to the galaxy. Astronomers measured the galaxy's distance at nearly 11 million light-years away, about 4 million light-years farther than the old distance.

"This was a serendipitous discovery," Aloisi said. "Hubble didn't go deep enough to see the faintest red giant stars we were hunting for because the galaxy is farther away than we thought. However, by capturing the entire population of the brightest red giant stars, we were able to calculate a precise distance to NGC 1569 and resolve the puzzle about the galaxy's extreme starburst activity."

The results were published in the Oct. 20 issue of the Astrophysical Journal Letters.
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The Eastern Veil Nebula

2008-11-08T14:36:00.006Z

Click on Image to Enlarge - Credit & Copyright: Paul Mortfield, Stefano Cancelli

I know, I know Halloween is over, but I just had to bring this one of A Spectre in the Eastern Veil over from APoD.

Menacing flying forms and garish colours are a mark of the Halloween season. They also stand out in this cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape covering nearly 3 degrees on the sky in the constellation Cygnus, this portion of the eastern Veil spans only 1/2 degree, about the apparent size of the Moon.

That translates to 12 light-years at the Veil's estimated distance of 1,400 light-years from planet Earth. In this composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms in greenish hues. In the western part of the Veil lies another seasonal apparition, the Witch's Broom.
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Magic from Hubble

2008-11-05T08:59:00.005Z

STScI-PRC2008-37. Credit: NASA, ESA, and M. Livio (STScI)

Just a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a a pair of gravitationally interacting galaxies called Arp 147.

The left-most galaxy in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, exhibits a clumpy, blue ring of intense star formation.

The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.

The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.

This picture was assembled from WFPC2 images taken with three separate filters. The blue, visible-light, and infrared filters are represented by the colours blue, green, and red, respectively.

Arp 147 appears in the Arp Atlas of Peculiar Galaxies, compiled by Halton Arp in the 1960s and published in 1966.
The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, and it is more than 400 million light-years away from Earth.
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A Witch by Starlight

2008-10-31T14:19:00.003Z

A Witch by Starlight Credit & Copyright: Star Shadows Remote Observatory

By starlight this eerie visage shines in the dark, a crooked profile evoking its popular name, the Witch Head Nebula.

In fact, this entrancing telescopic portrait gives the impression the witch has fixed her gaze on Orion's bright supergiant star Rigel.

Spanning over 50 light-years, the dusty cosmic cloud strongly reflects nearby Rigel's blue light, giving it the characteristic color of a reflection nebula. Cataloged as IC 2118, the Witch Head Nebula is about 1,000 light-years away. Of course, you might see a witch this scary tonight, but don't panic. Have a safe and Happy Halloween!
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Great Orion Nebula

2008-10-27T07:25:00.000Z

Great Orion Nebulae Credit & Copyright: Tony Hallas

The Great Nebula in Orion, also known as M42, is one of the most famous nebulae in the sky. The star forming region's glowing gas clouds and hot young stars are on the right in this sharp and colourful two frame mosaic that includes the smaller nebula M43 near center and dusty, bluish reflection nebulae NGC 1977 and friends on the left.

Located at the edge of an otherwise invisible giant molecular cloud complex, these eye-catching nebulae represent only a small fraction of this galactic neighborhood's wealth of interstellar material.

Within the well-studied stellar nursery, astronomers have also identified what appear to be numerous infant solar systems. The gorgeous skyscape spans nearly two degrees or about 45 light-years at the Orion Nebula's estimated distance of 1,500 light-years.
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A Dark Pulsar in CTA1

2008-10-21T08:43:00.005+01:00

A Dark Pulsar in CTA 1 Credit: NASA, S. Pineault (DRAO)

Previously, the CTA 1 -- supernova remnant -- revealed a compact nebula, a bent jet, and a point source expected to be a pulsar - a rotating neutron star producing pulses at radio energies - all of which are characteristic of energetic, rotation-powered pulsars. But no radio pulses were detected.

Now NASA's recently deployed Fermi Space Telescope has solved the mystery with some of its initial observations indicating that the point source is pulsing at gamma-ray energies.

The strange source is the first of a class that might be dubbed "dark pulsars", rotating neutron stars that appear to pulse only in high-energy radiations. Such pulsars might not be detectable in radio or visible light if they emit those radiations into a narrow beam not seen from Earth. If true, our Galaxy might have more pulsars left for Fermi to discover.

Studying the gamma-ray properties of pulsars gives valuable clues to physics of the emission regions on neutron stars. In this graphic, the pulsar's position is indicated in the wider CTA 1 supernova remnant. An artist's illustration of the pulsar beaming at gamma-ray energies is shown in the inset.
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Bright Bolide

2008-10-12T09:35:00.000+01:00

Credit & Copyright: Howard Edin (Oklahoma City Astronomy Club)

On September 30, a spectacular bolide or fireball meteor surprised a group of amateur astronomers enjoying dark night skies over the Oklahoma panhandle's Black Mesa State Park in the Midwestern US. Flashing past familiar constellations Taurus (top) and Orion, the extremely bright meteor was captured by a hillside camera overlooking the 2008 Okie-Tex Star Party.

Astronomy enthusiast Howard Edin reports that he was looking in the opposite direction at the time, but saw the whole observing field light up and at first thought someone had turned on their car headlights. So far the sighting of such a bright bolide meteor, produced as a space rock is vaporized hurtling through Earth's atmosphere, really is a matter of luck. But that could change.

Earlier this week the discovery and follow-up tracking of tiny asteroid 2008 TC3 allowed astronomers to predict the time and location of its impact with the atmosphere. While no ground-based sightings of the fireball seem to have been reported, this first ever impact prediction was confirmed by at least some detections of an air burst and bright flash on October 7th over northern Sudan.
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The Circinus Galaxy

2008-10-07T07:19:00.001+01:00

Credit: X-ray (NASA/CXC/Columbia/F.Bauer et al);
Optical (NASA/STScI/UMD/A.Wilson et al.)

This composite image shows the central regions of the nearby Circinus galaxy, located about 12 million light years away. Data from NASA's Chandra X-ray Observatory is shown in blue and data from the Hubble Space telescope is shown in yellow ("I-band"), red (hydrogen emission), cyan ("V-band") and light blue (oxygen emission). The bright, blue source near the lower right hand corner of the image is the supernova SN 1996cr, that has finally been identified over a decade after it exploded.

Optical images from the archives of the Anglo-Australian Telescope in Australia show that SN 1996cr exploded between February 28, 1995 and March 15, 1996. Among the five nearest supernovas of the last 25 years, SN 1996cr is the only one that was not seen shortly after the explosion. It may not have been noticed by astronomers at the time because it was only visible in the southern hemisphere, which is not as widely monitored as the northern.

The supernova was first singled out in 2001 as a bright, variable object in a Chandra image. Despite some exceptional properties, its nature remained unclear until years later, when scientists were able to confirm this object was a supernova. Clues in data from the European Southern Observatory's Very Large Telescope led the team to search through data archives from 18 different telescopes, both in space and on the ground, nearly all of which was from archives. This is a remarkable example of the new era of `Internet astronomy'.

The Circinus galaxy is a popular target for astronomers because it contains a supermassive black hole that is actively growing, and it shows vigorous star formation. It is also nearby, at only about 4 times the distance of M31.
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Overlapping Galaxies

2008-09-24T08:45:00.003+01:00

NASA's Hubble Space Telescope has captured a rare alignment between two spiral galaxies. The outer rim of a small, foreground galaxy is silhouetted in front of a larger background galaxy. Skeletal tentacles of dust can be seen extending beyond the small galaxy's disk of starlight.

Such outer dark dusty structures, which appear to be devoid of stars, like barren branches, are rarely so visible in a galaxy because there is usually nothing behind them to illuminate them. Astronomers have never seen dust this far beyond the visible edge of a galaxy. They do not know if these dusty structures are common features in galaxies.

Understanding a galaxy's colour and how dust affects and dims that colour are crucial to measuring a galaxy's true brightness. By knowing the true brightness, astronomers can calculate the galaxy's distance from Earth.

Astronomers calculated that the background galaxy is 780 million light-years away. They have not as yet calculated the distance between the two galaxies, although they think the two are relatively close, but not close enough to interact. The background galaxy is about the size of the Milky Way Galaxy and is about 10 times larger than the foreground galaxy.

Most of the stars speckled across this image belong to the nearby spiral galaxy NGC 253, which is out of view to the right. Astronomers used Hubble's Advanced Camera for Surveys to snap images of NGC 253 when they spied the two galaxies in the background. From ground-based telescopes, the two galaxies look like a single blob. But the Advanced Camera's sharp "eye" distinguished the blob as two galaxies, cataloged as 2MASX J00482185-2507365.

Hubble Heritage release The images were taken on Sept. 19, 2006.
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Upside down Rainbow

2008-09-16T09:45:00.001+01:00

The sky is smiling @ Cambridge Evening News

EXCEPTIONAL atmospheric conditions created a rare and stunning display in the skies above Cambridge. At 4.45pm on Sunday, a circumzenithal arc - which looks like a bright, upside down rainbow - was visible above the city.

Cambridge-based astronomer Jacqueline Mitton captured the stunning sight, caused by sunlight being refracted through ice crystals high in the atmosphere, with her camera.

The phenomenon is rarely seen outside the polar regions.

She said: "I've never seen anything like it before - and I'm 60." "The conditions have to be just right: you need the right sort of ice crystals and the sky has to be clear." "It's quite surprising for this to occur somewhere like Cambridge, usually it is in places that are colder."

"We're not sure how big an area it was visible over, but it was certainly very impressive."

The intensity of the colours in the rainbow was heightened by the sun being at the optimum spot in the sky - 22 degrees. And the sky was made even more dazzling with the presence of "sun dogs" - gleaming spots on a halo around the sun - appearing near the phenomenon in the afternoon sky.

Dr Mitton said: "It was just an amazing combination of factors that happened at the right time."

Jacqueline's husband Simon, an astronomy writer, said: "The circumzenithal arc is a quarter circle, pointing toward the setting sun." "The 'rainbow' is much brighter and more concentrated than a rainfall rainbow."

A Met Office spokeswoman said: "They are fairly rare." "It is convex to the sun and is formed by refraction in suitably-oriented ice crystals and may show vivid rainbow colouring, as in this case."
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Hawking -vs- Higgs

2008-09-12T07:30:00.004+01:00

Stephen Hawking's recent quip that it might be more interesting if the Large Hadron Collider didn't find any Higgs bosons, sets the scene for the ultimate scientific showdown.

Getting upset at Stephen Hawking might not sound like a smart thing for a scientist to do, but when you consider that it's Professor Peter Higgs himself you can sort of see his point.

The Large Hadron Collider LHC @ CERN in Switzerland is the first particle accelerator able to access the energies necessary to reveal the Higgs particle (if it's there) or set an awful lot of people scurrying back to their blackboards (if it's not).
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Milky Way Road Trip

2008-09-08T07:55:00.002+01:00

Credit & Copyright: Tunç Tezel (TWAN) - Click on Image to Enlarge.

In search of planets and the summer Milky Way. An evening road trip driving the winding road up Uludag, a mountain near Bursa, Turkey, one is rewarded by this beautiful skyview to the south.

Near the center, bright planet Jupiter outshines the city lights below and the stars of the constellation Sagittarius.

Above the mountain peaks, an arcing cloud bank seems to lead to the Milky Way's own cloudy apparition plunging into the distant horizon. In Turkish, Uludag means Great Mountain. Uludag was known in ancient times as the Mysian Olympus.
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Monster Galaxy

2008-08-31T10:16:00.006+01:00

The active galaxy NGC 1275 is also a well-known radio source (Perseus A) and a strong emitter of X-rays due to the presence of a black hole in the center of the galaxy. The behemoth also lies at the center of the cluster of galaxies known as the Perseus Cluster. By combining multi-wavelength images into a single composite, the dynamics of the galaxy are more easily visible. Detail and structure from x-ray, optical and radio wavelengths combine for an aesthetically pleasing, but nonetheless violent depiction of events going on at the heart of the galaxy.

Chandra data from the Advanced CCD Imaging Spectrometer (ACIS) covers X-ray energies from 0.3-7keV. Hubble data from the Advanced Camera for Surveys covers optical wavelengths in the red, green and blue. Radio data from NRAO's Very Large Array at 328 MHz was also used. In the composite image, the X-ray data contribute to the soft violet shells around the outside of the center. The pinkish lobes toward the center of the galaxy are from radio frequencies.

The radio emission, tracing jets from the black hole, fills the X-ray cavities. Dust lanes, star-forming regions, hydrogen filaments, foreground stars, and background galaxies are contributions from the Hubble optical data.

Credit X-ray: NASA/CXC/IoA/A.Fabian et al.; Radio: NRAO/VLA/G. Taylor; Optical: NASA/ESA/Hubble Heritage (STScI/AURA) & Univ. of Cambridge/IoA/A. Fabian

Constellation Perseus. Also Known As NGC 1275. Distance Estimate About 250 million light years. Scale Image is 3.87 arcmin across. Category Groups & Clusters of Galaxies. Coordinates (J2000) RA 03h 19m 47.60s Dec +41° 30' 37.00
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Faster than Light

2008-08-17T13:29:00.003+01:00

Traveling Faster Than the Speed of Light

The method is based on the Alcubierre drive, which proposes expanding the fabric of space behind a ship and shrinking space-time in front of the ship. The ship would not actually move, rather the ship would sit in a bubble between the expanding and shrinking space-time dimensions

Two Baylor University scientists have come up with a new method to cause a spaceship to effectively travel faster than the speed of light, without breaking the laws of physics.

Dr. Gerald Cleaver, associate professor of physics at Baylor theorizes that by manipulating the extra spatial dimensions of string theory around a spaceship with an extremely large amount of energy, it would create a "bubble" that could cause the ship to travel faster than the speed of light.

To create this bubble, the Baylor physicists believe manipulating the 10th spatial dimension would alter the dark energy in three large spatial dimensions: height, width and length.

Cleaver said positive dark energy is currently responsible for speeding up the expansion rate of our universe as time moves on, just like it did after the Big Bang, when the universe expanded much faster than the speed of light for a very brief time.

"Think of it like a surfer riding a wave," said Cleaver, who co-authored the paper with Obousy about the new method. "The ship would be pushed by the spatial bubble and the bubble would be traveling faster than the speed of light."

The method is based on the Alcubierre drive, which proposes expanding the fabric of space behind a ship and shrinking space-time in front of the ship. The ship would not actually move, rather the ship would sit in a bubble between the expanding and shrinking space-time dimensions.

Since space would move around the ship, the theory does not violate Einstein's Theory of Relativity, which states that it would take an infinite amount of energy to accelerate a massive object to the speed of light.

String theory suggests the universe is made up of multiple dimensions. Height, width and length are three dimensions, and time is the fourth dimension. String theorists use to believe that there were a total of 10 dimensions, with six other dimensions that we can not yet identify because of their incredibly small size.

A new theory, called M-theory, takes string theory one step farther and states that the "strings" that all things are made of actually vibrate in an additional spatial dimensional, which is called the 10th dimension.

It is by changing the size of this 10th spatial dimension that Baylor researchers believe could alter the strength of the dark energy in such a manner to propel a ship faster than the speed of light.

The Baylor physicists estimate that the amount of energy needed to influence the extra dimension is equivalent to the entire mass of Jupiter being converted into pure energy for a ship measuring roughly 10 meters by 10 meters by 10 meters.

"That is an enormous amount of energy," Cleaver said. "We are still a very long ways off before we could create something to harness that type of energy."
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Bridge of Sighs

2008-08-10T06:00:00.001+01:00

Photo credit: Neorelix

...supposedly the sound of despair as students traipse out of exams and over this bridge.

The Bridge of Sighs was supposedly Queen Victoria's favourite place in the city - but only because she hadn't been to the Live and Let Live (which btw is having a 5 yr anniversary do this Saturday) or The Free Press obviously.

Inspired by the 231 years-older one in Venice (Really??) it's found between 3rd and New Courts of St John's College (1511). Wacky students occasionally suspend cars beneath it...
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Order from Chaos

2008-08-06T07:35:00.000+01:00

As you can see I've been trying to restore some order in the Universe.

Building a wall around the villa, and in the process getting a bit of a tan between dips in the pool. The villa by the way is in the plot behind the wall (unseen to the right). I'm standing outside the wall on the drive onto the main road.

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And here is the pool

2008-08-05T07:39:00.000+01:00

Nearby Galaxy Metropolis

2008-08-03T14:01:00.000+01:00

This image is a composite of visible (or optical), radio, and X-ray data of the giant elliptical galaxy, M87.

M87 lies at a distance of 60 million light years and is the largest galaxy in the Virgo cluster of galaxies. Bright jets moving at close to the speed of light are seen at all wavelengths coming from the massive black hole at the center of the galaxy.

It has also been identified with the strong radio source, Virgo A, and is a powerful source of X-rays as it resides near the center of a hot, X-ray emitting cloud that extends over much of the Virgo cluster. The extended radio emission consists of plumes of fast-moving gas from the jets rising into the X-ray emitting cluster medium.

In X-rays, M87 also reveals evidence for a series of outbursts from the central supermassive black hole. The loops and bubbles in the hot, X-ray emitting gas are relics of small outbursts from close to the black hole.

Other interesting features in M87 are narrow filaments of X-ray emission, which may be due to hot gas trapped by magnetic fields. One of these filaments is over 100,000 light years long, and extends below and to the right of the center of M87 in almost a straight line.

The optical data of M87 were obtained with Hubble's Advanced Camera for Surveys in visible and infrared filters (data courtesy of P. Cote, Herzberg Institute of Astrophysics, and E. Baltz, Stanford University). Wide-field optical data of the center of the Virgo Cluster were also provided by R. Gendler (Copyright Robert Gendler 2006).

The X-ray data were acquired from the Chandra X-ray Observatory's Advanced CCD Imaging Spectrometer (ACIS), and were provided by W. Forman (Harvard-Smithsonian Center for Astrophysics) et al. The radio data were obtained by W. Cotton and also archive processing using the National Radio Astronomy Observatory's Very Large Array (NRAO/VLA) near Socorro, New Mexico.
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A Stellar Jewel Box

2008-08-01T09:38:00.000+01:00

Open Cluster NGC 290: A Stellar Jewel Box - Click to Enlarge
Credit: ESA & NASA; Acknowledgement: E. Olszewski (U. Arizona)

Jewels don't shine this bright -- only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and colour.

The photogenic cluster, pictured above, was captured recently by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars.

NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65 light years across. NGC 290 and other open clusters are good laboratories for studying how stars of different masses evolve, since all the open cluster's stars were born at about the same time.
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The First Stars

2008-07-31T07:02:00.000+01:00

How the First Stars Were Born

A new supercomputer simulation offers the most detailed view yet of how the first stars evolved after the Big Bang. The model follows the simpler physics that ruled the early universe to see how cold clumps of gas eventually grew into giant star embryos.

"Until you put that physics in the code, you can't evaluate how the first protostars formed," said Lars Hernquist, an astrophysicist at Harvard University whose early-stars model is detailed in this week's issue of the journal Science.

Mysterious "dark matter" provided the first gravitational impetus for hydrogen and helium gas to start clumping together, Hernquist said. The gas began releasing energy as it condensed, forming molecules from atoms, which further cooled the clump and allowed for even greater condensing.

Unlike previous models, the latest simulation takes this cooling process of "complex radiative transfer" into account, said Nagoya University astrophysicist Naoki Yoshida, who headed up the modeling project.

Eventually gravity could not condense the gas cloud any further, because the densely-packed gas exerted a pressure against further collapse. That equilibrium point marked the beginning of an embryonic star, called a protostar by astronomers.

Simulation runs show that the first protostar likely started with just 1 percent the mass of our sun, but would have swelled to more than 100 solar masses in 10,000 years.

"No simulation has ever gotten to the point of identifying this important stage in the birth of a star," Hernquist noted.

The first protostars reached such massive size because they consisted of mainly simple elements such as hydrogen and helium. That bloated existence means the stars which eventually form from such protostars could create heavier elements such as oxygen, carbon, nitrogen and iron in their fiery furnaces.

CfA Press Release
Simulating the first stars by Centauri Dreams.
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The True Colour of Blackholes

2008-07-23T07:35:00.000+01:00

Schematic display of the polarisation observation. The red star-like object in the upper left is one of the quasars observed. The light is thought to originate from the accretion disk with a strong contamination from messy dust clouds, as shown by the drawing on the upper-right panel. When we put in a polarisation filter, these clouds are suppressed from view, giving us the true colour of the accretion disk, as shown in the two lower panels.

Image: M. Kishimoto with cloud image by M. Schartmann

The central regions of active galaxies are thought to be powered by supermassive black holes accreting gas from their surrounds. An important ingredient of the so-called "standard model" of Active Galactic Nuclei or AGN is a massive accretion disk which is believed to be the source of most of the radiation from the AGN. Until recently, the presence of such accretion disks was only theoretically assumed. An international team of astronomers, led by Makoto Kishimoto from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, found a clever way to get around observational problems caused by the dust environment of the nucleus. They could eliminate the influence of dust contamination by observing polarised emission directly from the central region of the AGN. Thus they could show that the spectrum of the central source is as blue as expected from theory, verifying a long-standing prediction about the intensely luminous radiation emitted by these accretion disks. The results are published in this week's issue of the journal "Nature".

Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding "accretion disk".

Such black holes and their accretion disks are thought to be in a messy environment - surrounded by many clouds of dust. This has confused astronomers who tried to study the spectrum of the black hole vicinity - the strong emission from these clouds badly contaminates their precious spectrum. "Astronomers were puzzled by the fact that the most extensively studied models of these disks couldn't quite be reconciled with some of the observations, in particular, with the fact that these disks did not appear as blue as they should be", explains Makoto Kishimoto from MPIfR. However, an international team of astronomers, led by Kishimoto, found a clever way to get around this. Since the disk light is scattered in the vicinity of the disk and thus appears polarised, they could use the polarised light to separate the disk from the surrounding dust clouds.

For their observations in the infrared the researchers used polarising filters at some of the largest telescopes on Earth - one of the 8.2m VLT telescopes at the Paranal observatory of ESO in Chile as well as the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea in Hawaii. This enabled them to get rid of emission from hot dust outside the accretion disk, and they could demonstrate that the disk spectrum is as blue as predicted.

Dr. Robert Antonucci of the University of California at Santa Barbara, a fellow investigator, says: "Our understanding of the physical processes in the disk is still rather poor, but now at least we are confident of the overall picture." The disk behaviour found in the paper is expected to originate in the outermost region of the disk, where important questions are yet to be answered: how and where the disk ends and how material is being supplied to the disk. "In the near future, our new method may pioneer the way to address these questions", says Makoto Kishimoto.
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Binary Pulsar System

2008-07-06T07:55:00.002+01:00

The double pulsar PSR J0737-3039A/B consists of a binary system made up of two pulsars in a 2.4-hour orbit. Each pulsar emits radio waves along its magnetic poles that illuminate Earth-based radio-telescopes like rotating lighthouse beacons as they spin; one every 23 milliseconds and the other every 2.8 seconds.

The fortunate almost-perfect alignment of our line of sight with the orbital plane of the system gives rise to an eclipse of the 23-ms pulsar, once per orbit, as it moves behind its 2.8-s pulsar companion. The eclipse is created by the magnetosphere of the 2.8-s pulsar, a region in which a dense cloud of plasma is trapped by the magnetic field of the pulsar.

These eclipses allow us to infer the orientation the 2.8-s pulsar since changes in the geometry would affect the way that light emitted by the other pulsar is transmitted to us during the eclipse.

According to classical Newtonian physics, the spin axis about which a star rotates should remain fixed with respect to the background stars as it orbits another star. Einstein's general relativity predicts, however, that the spin axis should slowly precess, like the gentle wobble of a tilted spinning top.
(Credit: Daniel Cantin, DarwinDimensions. McGill University)
[+/-] Click here to expand

Researchers at McGill University's Department of Physics -- along with colleagues from several countries -- have confirmed a long-held prediction of Albert Einstein's theory of general relativity, via observations of a binary-pulsar star system.
Their results were published July 3 in the journal Science.

Pulsars are small, ultradense stellar objects left behind after massive stars die and explode as supernovae. They typically have a mass greater than that of our Sun, but compressed to the size of a city like Montreal. They spin at staggering speeds, generate huge gravity fields and emit powerful beams of radio waves along their magnetic poles.

These illuminate Earth-based radio-telescopes like rotating lighthouse beacons as the pulsar spins. More than 1,700 pulsars have been discovered in our galaxy, but PSR J0737-3039A/B, discovered in 2003, is the only known double-pulsar system; that is, two pulsars locked into close orbit around one another. The two pulsars are so close to each other, in fact, that the entire binary could fit within our Sun. PSR J0737-3039A/B lies about 1,700 light years from Earth.

This new test of Einstein's theory was led by McGill astrophysics PhD candidate René Breton and Dr. Victoria Kaspi, leader of the McGill University Pulsar Group.

"A binary pulsar creates ideal conditions for testing general relativity's predictions because the larger and the closer the masses are to one another, the more important relativistic effects are," Breton explained.

"Binary pulsars are the best place to test general relativity in a strong gravitational field," agreed Kaspi, McGill's Lorne Trottier Chair in Astrophysics and Cosmology and Canada Research Chair in Observational Astrophysics. ""Einstein's theory predicted that, in such a field, an object's spin axis should slowly change direction as the pulsar orbits around its companion. Imagine a spinning top when its slightly non-vertical: the spin axis slowly changes direction, an elegant motion called 'precession.'"

The researchers discovered that one of the two pulsars is indeed precessing -- just as Einstein's 1915 theory predicts. If Einstein had been wrong, the pulsar wouldn't be precessing, or would precess in some other way.

Pulsars are too small and too distant to to allow us to directly observe their orientation, the researchers explained. However, they soon realized they could make such measurements using the eclipses visible when one of the twin pulsars passes in front of its companion. When this occurs, the magnetosphere of the first pulsar partly absorbs the radio "light" being emitted from the other, which allows the researchers to determine its spatial orientation. After four years of observations, they determined that its spin axis precesses just as Einstein predicted.

Even though spin precession has been observed in Earth's solar system, differences between general relativity and alternative theories of gravity might only shake out in extremely powerful gravity fields such as those near pulsars, Breton said.

"However, so far, Einstein's theory has passed all the tests that have been conducted, including ours. We can say that if anyone wants to propose an alternative theory of gravity in the future, it must agree with the results that we have obtained here."

Breton, Kaspi and colleagues in Canada, the United Kingdom, the U.S., France and Italy studied the twin-pulsar using the 100-metre Robert C. Byrd Green Bank Radio Telescope at the National Radio Astronomy Observatory in Green Bank, WV.

"I think that if Einstein were alive today, he would have been absolutely delighted with these results," said Dr. Michael Kramer, Associate Director of the Jodrell Bank Centre for Astrophysics at Manchester University. "Not only because it confirms his theory, but also because of the novel way the confirmation came about."

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Supernova Remnant

2008-07-02T07:28:00.004+01:00

A new star, likely the brightest supernova in recorded human history, lit up planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion, found in the southerly constellation of Lupus, still puts on a cosmic light show across the electromagnetic spectrum. In fact, this composite view includes X-ray data in blue from the Chandra Observatory, optical data in yellowish hues, and radio image data in red.

Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a white dwarf star. Part of a binary star system, the compact white dwarf gradually captured material from its companion star. The buildup in mass finally triggered a thermonuclear explosion that destroyed the dwarf star.

Because the distance to the supernova remnant is about 7,000 light-years, that explosion actually happened 7,000 years before the light reached Earth in 1006. Shockwaves in the remnant accelerate particles to extreme energies and are thought to be a source of the mysterious cosmic rays.

For Zoomable Image of SN1006 from Hubble Click here

This image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago.
[+/-] Click here to expand

On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.

It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.

In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas.

The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed "snapshot" of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight.

Today we know that SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image as displayed, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left.

SN 1006 resides within our Milky Way Galaxy. Located more than 14 degrees off the plane of the galaxy's disk, there is relatively little confusion with other foreground and background objects in the field when trying to study this object. In the Hubble image, many background galaxies (orange extended objects) far off in the distant universe can be seen dotting the image. Most of the white dots are foreground or background stars in our Milky Way galaxy.

This image is a composite of hydrogen-light observations taken with Hubble's Advanced Camera for Surveys in February 2006 and Wide Field Planetary Camera 2 observations in blue, yellow-green, and near-infrared light taken in April 2008. The supernova remnant, visible only in the hydrogen-light filter was assigned a red hue in the Heritage colour image.

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Hawking & Colleagues

2008-06-29T20:00:00.010+01:00

WHY was the big bang so very big? It has been a struggle to explain why the infant universe expanded so rapidly.

The idea that the universe expanded at a blistering rate in the first 10-34 seconds after the big bang was proposed to explain why regions of the universe separated by vast distances have such a similar background temperature: before inflation occurred, these regions would have been close together with similar properties.

But just why the universe inflated in the first place remains a mystery. WHY was the big bang so very big? It has been a struggle to explain why the infant universe expanded so rapidly.

Now Stephen Hawking at the University of Cambridge, and colleagues, think they are close to perfecting an answer - by treating the early cosmos as a quantum object with a multitude of alternative universes that gradually blend into ours.

Quantum mechanics is awash with strange ideas and can shed new light on inflation, which came in the wake of when the universe itself was around the size of an atom.

By quantum lore, when a particle of light travels from A to B, it does not take one path but explores every one simultaneously, with the more direct routes being used more heavily.

This is called a sum over histories and Prof Hawking and Prof Hertog propose the same thing for the cosmos.

In this theory, the early universe can be described by a mathematical object called a wave function and, in a similar way to the light particle, the team proposed two years ago that this means that there was no unique origin to the cosmos: instead the wave function of the universe embraced a multitude of means to develop.

This is very counter intuitive: they argued the universe began in just about every way imaginable (and perhaps even some that are not). Out of this profusion of beginnings, like a blend of a God’s eye view of every conceivable kind of creation, the vast majority of the baby universes withered away to leave the mature cosmos that we can see today.

[+/-] Click here to expand

But, like any new idea, there were problems. The professors found that they could not explain the rapid expansion - inflation - of the universe, evidence of which is left behind all around us in what is called the cosmic microwave background, in effect the echo of the big bang, a relic of creation that can be measured with experiments on balloons and on space probes.

Now, in a paper in Physical Review Letters with Prof James Hartle of the University of California, Santa Barbara, they realised that their earlier estimates of inflation were wrong because they had not fully thought through the connection between, on the one hand, their theoretical predictions and, on the other, our observations of the echo.

At first, they found that the most probable history of the cosmos had only undergone "a little bit of inflation at the beginning, contradicting the observations," said Prof Hertog. Now, after a correction to take account of how the data we have on inflation is based on only a view of a limited volume of the universe, they find that the wave function does indeed predict a long period of inflation.

"This proposal, with volume weighting, can explain why the universe inflated," Prof Hawking tells New Scientist. By taking into account that we have a parochial view of the cosmos, the team has come up with a radical new take on cosmology.

Most models of the universe are bottom-up, that is, you start from well-defined initial conditions of the Big Bang and work forward. However, Prof Hertog and Prof Hawking say that we do not and cannot know the initial conditions present at the beginning of the universe. Instead, we only know the final state - the one we are in now.

Their idea is therefore to start with the conditions we observe today - like the fact that at large scales one does not need to adopt quantum lore to explain how the universe (it behaves classically, as scientists say) - and work backwards in time to determine what the initial conditions might have looked like.

In this way, they argue the universe did not have just one unique beginning and history but a multitude of different ones and that it has experienced them all.

The new theory is also attractive because it fits in with string theory - the most popular candidate for a "theory of everything."

String theory allows the existence of an" unimaginable multitude of different types of universes in addition to our own," but it does not provide a selection criterion among these and hence no explanation for why our universe is, the way it is", says Prof Hertog.

"For this, one needs a theory of the wave function of the universe."

And now the world of cosmology has one. The next step is to find specific predictions that can be put to the test, to validate this new view of how the cosmos came into being.
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Proof that a mysterious force called “dark energy” is pushing the universe to expand endlessly at a faster and faster rate was selected as the “Breakthrough of the Year” by the editors of Science magazine.

The bizarre idea that some unknown force exists in the universe that is opposing gravity and flinging galaxies away from each other at an accelerating clip was first proposed in 1998. New studies in 2003 proved that the force does exist, and this discovery captured the top prize by the editors of Science as the year’s most important scientific development.

“It is one of the ultimate discoveries in basic science,” said Don Kennedy, editor-in-chief of the journal. “It stirs our imagination even though it challenges our ability to understand.”

“No longer are scientists trying to confirm the existence of dark energy,” the journal reported in its Friday issue. “Now they are trying to find out what dark energy is made of, and what it tells us about the birth and evolution of the universe.”

The editors also selected nine other research advances, ranging from gamma ray research to the evidence of global warming's effects to the effects of RNA on genes. All the selections, the journal said in a statement, were chosen “for their profound implications for society and the advancement of science.”

Expanding universe
Proof for the existence of the “dark force” came from two studies that probed the very early universe — back to less than 400,000 years after the Big Bang — and confirmed that the universe was expanding at a faster rate.

The Wilkinson Microwave Anisotropy Probe telescope analyzed the cosmic microwave radiation background, an echo from the Big Bang, and determined the age and composition of the universe. It confirmed that only 4 percent is ordinary matter, the stuff seen every day, and 23 percent is a cold, dark matter composed of unknown particles. The rest, some 73 percent, of the universe is dark energy.

The study also narrowed the proven age of the universe to 13.7 billion years, plus or minus a few hundred thousand years. Prior estimates had been between 12 billion and 15 billion years.
Another study, the Sloan Digital Sky Survey, mapped the distribution of a quarter-million galaxies and confirmed again the domination of dark energy.

Of the dark energy finding, the journal said: “It is, perhaps, a sign that scientists will finally begin to understand the beginning.”

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Star Streams

2008-06-22T16:41:00.003+01:00

The Star Streams of NGC 5907
Image Credit & Copyright: R Jay Gabany (Blackbird Observatory) - collaboration; D.Martínez-Delgado(IAC, MPIA), J.Peñarrubia (U.Victoria) I. Trujillo (IAC) S.Majewski (U.Virginia), M.Pohlen (Cardiff).

Grand tidal streams of stars seem to surround galaxy NGC 5907. The arcing structures form tenuous loops extending more than 150,000 light-years from the narrow, edge-on spiral, also known as the Splinter or Knife Edge Galaxy. Recorded only in very deep exposures, the streams likely represent the ghostly trail of a dwarf galaxy -- debris left along the orbit of a smaller satellite galaxy that was gradually torn apart and merged with NGC 5907 over four billion years ago. Ultimately this remarkable discovery image, from a small robotic observatory in New Mexico, supports the cosmological scenario in which large spiral galaxies, including our own Milky Way, were formed by the accretion of smaller ones. NGC 5907 lies about 40 million light-years distant in the northern constellation Draco.
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Solstice Moonrise

2008-06-20T00:34:00.002+01:00

Solstice Moonrise, Cape Sounion. Click on pic to Enlarge
Credit & Copyright: Anthony Ayiomamitis (TWAN)

Today's solstice marks the northernmost point of the Sun's annual motion through planet Earth's sky and the astronomical beginning of the northern hemisphere's summer. But only two days ago, the Full Moon nearest the solstice rose close to the ecliptic plane opposite the Sun, near its southernmost point for the year. Astronomer Anthony Ayiomamitis recorded this dramatic picture of the solstice Full Moon rising above Cape Sounion, Greece.

The twenty-four hundred year old Temple of Poseidon lies in the foreground, also visible to sailors on the Aegean Sea. In this well-planned single exposure, a telescopic lens makes the Moon loom large, but even without optical aid casual skygazers often find the Full Moon looking astonishingly large when seen near the horizon. That powerful visual effect is known as the Moon Illusion.
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Cosmic Web

2008-05-30T11:19:00.006+01:00

Credit: NASA, ESA, and A. Feild (STScI)

This illustration shows how the Hubble Space Telescope searches for missing ordinary matter, called baryons, by looking at the light from quasars several billion light-years away. Imprinted on that light are the spectral fingerprints of the missing ordinary matter that absorbs the light at specific frequencies (shown in the colourful spectra at right). The missing baryonic matter helps trace out the structure of intergalactic space, called the "cosmic web."

Credit: NASA, ESA, and E. Hallman (University of Colorado, Boulder)

This graphic represents a slice of the spider-web-like structure of the universe, called the "cosmic web." These great filaments are made largely of dark matter located in the space between galaxies. The Hubble Space Telescope probed the structure of intergalactic space to look for missing ordinary matter, called baryons, that is gravitationally attracted to the cosmic web.
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Galaxies Collide

2008-05-22T17:33:00.008+01:00

Galaxies Collide in NGC 3256 - Credit: NASA, ESA, Hubble Heritage (STScI / AURA) - ESA/Hubble Collaboration, & A. Evans (UVa, NRAO, SUNYSB)

Galaxies don't normally look like this. NGC 3256 actually shows a current picture of two galaxies that are slowly colliding. Quite possibly, in hundreds of millions of years, only one galaxy will remain.

Today, however, NGC 3256 shows intricate filaments of dark dust, unusual tidal tails of stars, and a peculiar center that contains two distinct nuclei.

Although it is likely that no stars in the two galaxies will directly collide, the gas, dust, and ambient magnetic fields do interact directly. NGC 3256, part of the vast Hydra-Centaurus supercluster of galaxies, spans over 100 thousand light-years across and is located about 100 million light-years away.
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Black Holes get a kick

2008-05-01T16:34:00.005+01:00

A colossal black hole has been spotted exiting its home galaxy, kicked out after a huge cosmic merger took place. The event, seen for the first time, was announced on Tuesday April 29.

When two colliding galaxies finally merge, it is thought that the black holes at their cores may fuse together too. Astronomers theorize that the resulting energy release could propel the new black hole from its parent galaxy out into space, but no one has found such an event.

"We have observed the pre-merger stages of black holes," said Stefanie Komossa of the Max Planck Institute for extraterrestrial Physics, part of the team that made the new discovery. "But we haven't seen the actual merger event."

Komossa and her team have now detected the consequences of such a merger: a black hole in the process of leaving its home galaxy. "The consequence was that the merged black hole, the final product, the new black hole was expelled from the galaxy," Komossa said. The team's results are detailed in the May 10 issue of the journal Astrophysical Journal Letters.

Komossa explained that the theory behind these mergers follows from the observations that many galaxies have very massive black holes at their cores. If two galaxies with these black holes collide, "then it's sort of inevitable that these two black holes will come very close to each other."

The black holes may not merge right away though. "One possibility is that for a long time they just orbit each other," like binary stars, said Komossa.

The orbiting black holes might interact with a star or surrounding gas which could cause them to lose angular momentum. That would be a way to push them ever-closer towards each other.

Eventually, the black holes would fuse, and in the final coalescence, or merger, of these two black holes, a giant burst of gravitational waves is emitted. Since these waves are generally emitted in one preferred direction, the black hole is then kicked in the other direction.

The "kick" the black hole receives is akin to the recoil of a rifle. It can propel the black hole to speeds of up to several thousand kilometers per second, according theoretical simulations. The escaping black hole Komossa and her team observed was racing along at 5,900,000 mph (2,650 kilometers per second).

The pull of the galaxy's gravity is no match for these incredible speeds, and the black hole, "will inevitably go to intergalactic space," Komossa said.

In theory, these mergers and escapes would leave several black holes without galaxies and galaxies without black holes out in space.

Detecting black holes at the center of galaxies is a difficult process. Because their gravity is so powerful, light is trapped, which is why they're black. Only by looking at their effects on surrounding material are they presumed to exist, and this is typically done only with relatively nearby galaxies, so looking for a missing black hole in the center of a distant galaxy is a tricky prospect.

The evolution of black holes and galaxies is very closely linked, so what exactly the effect would be on the separated partners is uncertain and the subject of further research.

In simulations where a black hole receives a slightly weaker kick, it can't escape the galaxy's gravity, so it falls back and oscillates until it comes to rest again at the galaxy's core. Recent simulations of this situation showed that stellar orbits adjust to the yo-yoing black hole, "so it clearly has an effect on the core of the galaxy," Komossa said.
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Titanic Blast

2008-04-20T11:01:00.005+01:00

Credit: Hubble - News Release Number: STScI-2008-17

Peering across 7.5 billion light-years and halfway back to the Big Bang, NASA's Hubble Space Telescope has photographed the fading optical counterpart of a powerful gamma ray burst that holds the record for being the intrinsically brightest naked-eye object ever seen from Earth. For nearly a minute on March 19, this single "star" was as bright as 10 million galaxies.

Hubble Wide Field and Planetary Camera 2 (WFPC2) images of GRB 080319B, taken on Monday, April 7 show the fading optical counterpart of the titanic blast. Hubble astronomers had hoped to see the host galaxy where the burst presumably originated, but were taken aback that the light from the gamma ray burst is still drowning out the galaxy's light even three weeks after the explosion.

Hubble astronomers had hoped to see the host galaxy where the burst presumably originated, but were taken aback that the light from the GRB is still drowning out the galaxy's light even three weeks after the explosion. This is particularly surprising because it was such a bright GRB initially. Previously, bright bursts have tended to fade more rapidly, which fits in to the theory that brighter GRBs emit their energy in a more tightly confined beam. The slow fading leaves astronomers puzzling about just where the energy came from to power this GRB, and makes Hubble's next observations of this object in May all the more crucial.

Called a long-duration gamma ray burst, such events are theorized to be caused by the death of a very massive star, perhaps weighing as much as 50 times our Sun.

Such explosions, sometimes dubbed "hypernovae," are more powerful than ordinary supernova explosions and are far more luminous, in part because their energy seems to be concentrated into a blowtorch-like beam that, in this case, was aimed directly at Earth.

The Hubble exposure also shows field galaxies around the fading optical component of the gamma ray burst, which are probably unrelated to the burst itself.
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Star Formation in the Hinterlands from Centauri Dreams
Stellar Birth in the Galactic Wilderness from Universe Today
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Energetic Jets

2008-04-13T10:10:00.006+01:00

Credit: X-ray: NASA/CXC/ETH Zuerich/M.Guedel et al.; Illustration: NASA/CXC/M.Weiss

The image on the left from NASA's Chandra X-ray Observatory shows the first double-sided X-ray jet ever detected from a young star. A similar jet may have been launched from the young Sun and could have had a significant impact on the early solar system.

The young star, named DG Tau, is located in the Taurus star-forming region, about 450 light years from Earth. The bright source of X-rays in the middle of the image is DG Tau and the jet runs from the top left to the bottom right, extending to about 70 billion miles away from the star, or about 700 times the Earth-Sun separation.

A detailed analysis of this image, led by Manuel Guedel of the Institute of Astronomy, ETH Zuerich in Switzerland, shows that the counter jet (top-left) has, on average, higher energy X-rays than the forward jet (bottom-right). The likely explanation is that some of the lower energy X-rays in the counter jet are absorbed by a disk around DG Tau, as shown in the accompanying illustration (right graphic), showing the star, disk and the inner regions of the jets.

Highly energetic X-rays are also detected from the young star, partially absorbed by streams of material flowing from the disk onto the star. The disk itself is much too cool to be detected by Chandra. Note that the faint vertical feature below the star does not show evidence for an additional jet, but is a chance alignment of four photons.

The effects of the jet on its surroundings may be significant. Other researchers have previously suggested that X-rays from a typical young star can significantly affect the properties of its surrounding disk, by heating it and creating charged particles by stripping electrons off atoms (a process called ionization).

These X-rays will strike the disk at a low angle, mitigating their effects. In the case of the jets from DG Tau, the combined X-ray power in the jet is similar to that of a young star with relatively modest X-ray brightness, but X-rays from the jet have the advantage of striking the disk much more directly from above and below.

Guedel and colleagues argue that powerful X-ray jets might develop at some stage during the evolution of most young stars. They could, for example, have existed during the early stages of the solar system. DG Tau has about the same mass as the Sun, but is much younger with an age of about one million years, rather than about 4.5 billion years.

Since it is surrounded by a disk where planets may be forming, this new Chandra image suggests that the early Earth and its environment may have been bathed in X-rays from a jet like DG Tau's. Although it is unknown if such X-rays would have had a significant impact on the forming Earth, it is possible that they did more good than harm.

By ionizing the disk the X-rays may have generated turbulence, which could have had a substantial effect on the orbit of the young Earth, possibly helping to prevent it from making a disastrous plunge into the Sun. Furthermore, X-ray irradiation of disks may also be important in the production of complex molecules in the disk that will later end up on the forming planets.

The new X-ray observations of X-ray jets add new features to the already complex story of star and planet formation. The ionization and heating power of the X-rays rom jets will have to be included in future model calculations that will help scientists understand the physical evolution and chemical processing of environments that eventually lead to planets like those in our solar system.
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Galaxy Wars

2008-04-01T18:04:00.013+01:00

Galaxy Wars: M81 versus M82. - Click on Image to Enlarge.
Astronomy Picture of the Day. - Credit: Rainer Zmaritsch & Alexander Gross

On the left, surrounded by blue spiral arms, is spiral galaxy M81. On the right marked by red gas and dust clouds, is irregular galaxy M82.

This stunning vista shows these two mammoth galaxies locked in gravitational combat, as they have been for the past billion years.

The gravity from each galaxy dramatically affects the other during each hundred million-year pass. Last go-round, M82's gravity likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms. But M81 left M82 with violent star forming regions and colliding gas clouds so energetic the galaxy glows in X-rays.

In a few billion years only one galaxy will remain.
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Supernova Alert: “Supernova Factories” Discovered from Universe Today
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Planetary Nebula NGC2371

2008-03-04T21:01:00.004Z

Planetary Nebula NGC2371. Credit: Hubble Heritage

Probing a glowing bubble of gas and dust encircling a dying star, NASA's Hubble Space Telescope reveals a wealth of previously unseen structures.

The object, called NGC 2371, is a planetary nebula, the glowing remains of a Sun-like star. The remnant star visible at the center of NGC 2371 is the super-hot core of the former red giant, now stripped of its outer layers. Its surface temperature is a scorching 240,000 degrees Fahrenheit. NGC 2371 lies about 4,300 light-years away in the constellation Gemini.

The Hubble image reveals several remarkable features, most notably the prominent pink clouds lying on opposite sides of the central star. This colour indicates that they are relatively cool and dense, compared to the rest of the gas in the nebula.

A planetary nebula is an expanding cloud of gas ejected from a star that is nearing the end of its life. The nebula glows because of ultraviolet radiation from the hot remnant star at its center. In only a few thousand years the nebula will dissipate into space. The central star will then gradually cool down, eventually becoming a white dwarf, the final stage of evolution for nearly all stars.

The Hubble picture of NGC 2371 is a false-colour image, prepared from exposures taken through filters that detect light from sulfur and nitrogen (red), hydrogen (green), and oxygen (blue). These images were taken with Hubble's Wide Field Planetary Camera 2 in November 2007, as part of the Hubble Heritage program.
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Interstellar Gas Clouds

2008-03-01T09:30:00.002Z

Simulation of the collapse of an interstellar gas cloud into a massive star. The left side shows the whole cloud, and the right side shows a zoom-in around the massive star in the center. Credit: Mark Krumholz

Two scientists think they have decoded the gassy recipe to create stars as much as 100 times bigger than the sun, perhaps solving the mystery of their formation.

Mark Krumholz Princeton University in New Jersey and his colleague Christopher McKee of the University of California Berkeley used mathematical models to show how small stars can prime superstar formation, and detail their findings in the Feb. 28 issue of the journal Nature.

Gravity tends to break interstellar gas clouds into small pieces, preventing massive star formation, but little stars heating up a gas cloud can smooth it out, forcing gravity to create a huge star.

Star power
Although massive stars are about a million times rarer than the most common stars — those about 80 percent smaller than the sun — they are the movers and shakers of the universe.

"They're very rare, but massive stars are the dominant players in galaxies," Krumholz said. "They're the things that can push around and heat up interstellar gas - essentially where all stars come from."

He also explained that big stars seed the cosmos with elements that are required for life.

"They enrich the universe with metals from their supernovae," he said, noting that only enormous stars are powerful enough to fuse together small atoms and create the heavy materials.

Hot influence
To form a galactic superpower, Krumholz said an interstellar gas cloud needs to be thousands of times more dense than average. Problem is, gravity tends to break dense gas clouds into pieces and thwart massive star formation.

"The challenge isn't getting enough gas, it's getting the cloud into a small enough region and preventing its breakup," he said.

If a few small stars form within the cloud, Krumholz explained, they can heat up the cloud and increase its "column density," or pressure. The heating process prevents gravity from taking control of the cloud, breaking it up and forming only small stars.

"Heating up the gas helps pressure win over gravity's influence, ultimately forcing the gas cloud to collapse in a massive star," Krumholz said.

The new view of star formation highlights the rarity of massive stars — the only kind astronomers on Earth can see in distant galaxies — but leads to the possibility that more stars form in galaxies than previously thought.

"There may be significant parts of galaxies where massive stars can't form, but lower-mass stars like the sun can," Krumholz said.

We estimate the number of stars in a galaxy on the amount of light we see, and if massive stars are missing, then it's possible that we've dramatically underestimated the rate of star formation in distant regions of the universe.
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Massive Stars Need Their Smaller Siblings To Grow @ Universe Today
The Dragon - Beijing's New Monster Airport from The Daily Galaxy
X marks the spot in dark matter web from Space New Scientist
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Light echoes in RS Pup

2008-02-23T09:16:00.004Z

Nebula around Cepheid Star RS Pup. Credit: ESO

Astronomers calibrate the distance scale of the Universe
Taking advantage of the presence of light echoes, a team of astronomers have used an ESO telescope to measure, at the 1% precision level, the distance of a Cepheid - a class of variable stars that constitutes one of the first steps in the cosmic distance ladder.

Cepheids are pulsating stars that have been used as distance indicators since almost a hundred years. The new accurate measurement is important as, contrary to many others, it is purely geometrical and does not rely on hypotheses about the physics at play in the stars themselves.

The team of astronomers studied RS Pup, a bright Cepheid star located towards the constellation of Puppis ('the Stern') and easily visible with binoculars. RS Pup varies in brightness by almost a factor of five every 41.4 days. It is 10 times more massive than the Sun, 200 times larger, and on average 15 000 times more luminous.

RS Pup is the only Cepheid to be embedded in a large nebula, made of very fine dust that reflects some of the light emitted by the star.

Because the luminosity of the star changes in a very distinctive pattern, the presence of the nebula allows the astronomers to see light echoes and use them to measure the distance of the star.

"The light that travelled from the star to a dust grain and then to the telescope arrives a bit later than the light that comes directly from the star to the telescope," explains Kervella, lead-author of the paper reporting the result. "As a consequence, if we measure the brightness of a particular, isolated dust blob in the nebula, we will obtain a brightness curve that has the same shape as the variation of the Cepheid, but shifted in time."

This delay is called a 'light echo', by analogy with the more traditional echo, the reflection of sound by, for example, the bottom of a well.

The Principle of the Light Echo By monitoring the evolution of the brightness of the blobs in the nebula, the astronomers can derive their distance from the star: it is simply the measured delay in time, multiplied by the velocity of light (300 000 km/s). Knowing this distance and the apparent separation on the sky between the star and the blob, one can compute the distance of RS Pup.

From the observations of the echoes on several nebular features, the distance of RS Pup was found to be 6500 light years, plus or minus 90 light years.

"Knowing the distance to a Cepheid star with such an accuracy proves crucial to the calibration of the period-luminosity relation of this class of stars," says Kervella. "This relation is indeed at the basis of the distance determination of galaxies using Cepheids."

RS Pup is thus distant by about a quarter of the distance between the Sun and the Centre of the Milky Way. RS Pup is located within the Galactic plane, in a very populated region of our Galaxy.

The long-period Galactic Cepheid RS Puppis.I. A geometric distance from its light echoes. Author(s): P. Kervella, A. Mérand, L. Szabados, P. Fouqué, D. Bersier, E. Pompei, and G. Perrin
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The Formax Galaxy

2008-02-18T17:42:00.005Z

The center of the Fornax galaxy cluster is shown in this Chandra image. The galaxy NGC 1404 is shown below and to the left of the center. Hot gas is clearly visible in the center of the cluster and around NGC 1404. (Credit: NASA/CXC/Columbia U./C.Scharf et al.)

Using data from NASA's Chandra X-ray Observatory, scientists have reported the possible detection of a binary star system that was later destroyed in a supernova explosion. The new method they used provides great future promise for finding the detailed origin of these important cosmic events.

In an article on the February 14th issue of the journal Nature, Rasmus Voss of the Max Planck Institute for Extraterrestrial Physics in Germany and Gijs Nelemans of Radboud University in the Netherlands searched Chandra images for evidence of a much sought after, but as yet unobserved binary system - one that was about to go supernova. Near the position of a recently detected supernova, they discovered an object in Chandra images taken more than four years before the explosion.

The supernova, known as SN 2007on, was identified as a Type Ia supernova. Astronomers generally agree that Type Ia supernovas are produced by the explosion of a white dwarf star in a binary star system. However, the exact configuration and trigger for the explosion is unclear. Is the explosion caused by a collision between two white dwarfs, or because a white dwarf became unstable by pulling too much material off a companion star?
[+/-] Click here to expand

Answering such questions is a high priority because Type Ia supernovas are major sources of iron in the Universe. Also, because of their nearly uniform intrinsic brightness, Type Ia supernova are used as important tools by scientists to study the nature of dark energy and other cosmological issues.

"Right now these supernovas are used as black boxes to measure distances and derive the rate of expansion of the universe," said Nelemans. "What we're trying to do is look inside the box."

If the supernova explosion is caused by material being pulled off a companion star onto the white dwarf, fusion of this material on the surface of the star should heat the star and produce a strong source of X-radiation prior to the explosion. Once the supernova explosion occurs, the white dwarf is expected to be completely destroyed and then would be undetectable in X-rays. In the merger scenario, the intensity of X-ray emission prior to the explosion is expected to be much weaker.

Based on the detection of a fairly strong X-ray source at approximately the position of SN 2007on 4 years before the explosion, Voss and Nelemans conclude that the data support the scenario where matter is pulled off a companion star. The small number of X-ray sources in the field implies that there is only a small chance of an unrelated source being so close by coincidence. Also, the X-ray source has similar properties to those expected for fusion on a white dwarf, unlike most X-ray sources in the sky.

However, in follow-up studies, Voss, Nelemans and colleagues Gijs Roelofs (Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.) and Cees Bassa (McGill University, Canada) used higher-quality optical images to better determine the supernova's position. This work, which is not yet published, shows a small, but significant difference in the measured positions of the supernova and the X-ray source, suggesting the source may not be the progenitor.

Follow-up Chandra observations hint that the X-ray object has disappeared, but further observations are needed to finally decide whether the source was the progenitor or not.

The team is also applying this new method to other supernovas and has high hopes that they will eventually succeed in identifying the elusive cause of at least some of these explosions.

"We're very excited about opening up a new way of studying supernovas, even though we're not sure that we've seen this particular stellar bomb before it exploded," said Gijs Roelofs. "We're very confident that we'll learn a lot more about these important supernovas in the future."

Voss agrees that, even if the X-ray source is not found to be the progenitor of SN 2007on, the hunt is worth the effort.

"Finding the progenitor to one of these Type Ia supernovas is a great chase in astronomy right now," he said. "These supernovas are great tools for studying dark energy, but if we knew more about how they form they might become even better tools."

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Newborn Stars

2008-02-13T17:49:00.008Z

Click on Image to Enlarge.

Newborn stars peek out from the Rho Ophiuchi star-forming region in this dynamic image from NASA's Spitzer Space Telescope.

This representative-colour image of Rho Oph's main cloud, Lynds 1688, was created with data from Spitzer's infrared array camera, which has the highest spatial resolution of Spitzer's three imaging instruments, and its multiband imaging photometer, best for detecting cooler materials.

Blue represents light with a wavelength of 3.6 microns; green shows light of 8 microns; and red is 24-micron light.

The colours in this image reflect the relative temperatures and evolutionary states of the various stars. The youngest stars are surrounded by dusty disks of gas from which they, and their potential planetary systems, are forming. These young disk systems show up as red in this image. More evolved stars, which have shed their natal material, are blue.

The extended white nebula in the center right of the image is a region of the cloud which is glowing in infrared light due to the heating of dust by bright young stars near the right edge of the cloud. Fainter multi-hued diffuse emission fills the image. The colour of the nebulosity depends on the temperature, composition and size of the dust grains.

Spitzer Spies Young Stars in their Baby Blanket of Dust
Credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA
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The first fruits of 2008 original music by The Moody Minstrel
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Cosmic Fossil

2008-02-09T10:29:00.000Z

NGC 1132 A Mysterious Elliptical. Credit: Chanda

The NASA/ESA Hubble Space Telescope has captured a new image of the galaxy NGC 1132 which is, most likely, a cosmic fossil - the aftermath of an enormous multi-galactic pile-up, where the carnage of collision after collision has built up a brilliant but fuzzy giant elliptical galaxy far outshining typical galaxies.

The elliptical galaxy NGC 1132, seen in this latest image from Hubble, belongs to a category of galaxies called giant ellipticals. NGC 1132, together with the small dwarf galaxies surrounding it, are dubbed a "fossil group" as they are most likely the remains of a group of galaxies that merged together in the recent past.

In visible light NGC 1132 appears as a single, isolated, giant elliptical galaxy, but this is only the tip of the iceberg. Scientists have found that NGC 1132 resides in an enormous halo of dark matter, comparable to the amount of dark matter usually found in an entire group of tens or hundreds of galaxies.

It also has a strong X-ray glow from an abundant amount of hot gas - an amount normally only found in galaxy groups. Its X-ray glow extends over a region of space ten times larger than the 120,000 light-year radius it has in visible light. An X-ray glow that is equal in size to that of an entire group of galaxies.

The origin of fossil group systems remains a puzzle. The most likely explanation is that they are the end-products of a cosmic feeding frenzy in which a large cannibal galaxy devours all of its neighbours. A less likely explanation is that they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.

Many galaxies reside in groups that are gravitationally bound together, including our own Milky Way, which is part of the Local Group. Sometimes gravity makes galaxies collide and eventually merge into one single galaxy. There is strong evidence that the Milky Way is one such cannibal that has snacked on numerous smaller galaxies during its lifetime, inheriting their stars in the process.

Scientists are keenly studying the environment surrounding galaxies such as NGC 1132 using space telescopes like Hubble, and they try to trace the history of the formation these galaxies by analysing their properties.

In this Hubble image, NGC 1132 is seen surrounded by thousands of ancient globular clusters, swarming around the galaxy like bees around a hive. These globular clusters are likely to be the survivors of the disruption of their cannibalised parent galaxies that have been eaten by NGC 1132 and may reveal its merger history. In the background, there is a stunning tapestry of numerous galaxies that are much further away.

Elliptical galaxies are smooth and featureless. They contain hundreds of millions to trillions of stars, and their shapes range from nearly spherical to very elongated in shape. Their overall yellowish colour is a telltale sign of their great age. Because elliptical galaxies do not contain much cool gas they can no longer make new stars.

NGC 1132 is located approximately 320 million light-years away in the constellation of Eridanus, the River. This image of NGC 1132 was taken with Hubble's Advanced Camera for Surveys. Data obtained in 2005 and 2006 through green and near-infrared filters were used to produce a colour composite.
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Cosmic Fingers

2008-02-06T18:03:00.000Z

Click on Image to Enlarge. Credit: LiveScience

A giant gas finger emanating from two neighbouring galaxies has hooked into the starry disk of the Milky Way and is pulling all three galaxies closer. The hydrogen gas is actually the pointy end of the so-called Leading Arm of gas that streams ahead of two irregular galaxies called the Large and Small Magellanic Clouds.

The fate of these nearby galaxies, which are impacted by the Milky Way's gravity, has been somewhat of a mystery. The new findings suggest that the Magellanic Clouds will eventually merge with the Milky Way rather than zooming past.

Located about 160,000 light-years from Earth, the Large Magellanic Cloud (LMC) is only one-twentieth the diameter of our galaxy and contains one-tenth as many stars. The Small Magellanic Cloud resides 200,000 light-years from Earth and is about 100 times smaller than the Milky Way.

"We can determine exactly where this gas is plowing into the Milky Way," said research team leader Naomi McClure-Griffiths of CSIRO's Australia Telescope National Facility.

Called HVC306-2+230, the gas finger is gouging into our galaxy's starry disk about 70,000 light-years away from Earth. In the night sky, the contact point would be nearest the Southern Cross.

Until last year, astronomers thought the Magellanic Clouds had orbited our galaxy many times. This scenario held a gloomy outlook for the clouds, which were said to be doomed to be ripped apart and swallowed by the gravitational goliath.

But then new Hubble Space Telescope measurements revealed the clouds are paying our galaxy a one-time visit rather than being its lunch.

McClure-Griffiths' results, however, are more in line with the previous tale pegging the Milky Way and the Magellanic Clouds as long-time companions. McClure-Griffiths remarks that this isn't the final word and that both theories are still on the table.

By pointing out the spot of contact between the Leading Arm and our galactic disk, the recent study will help astronomers to predict where the clouds themselves will travel in the future.

"We think the Leading Arm is a tidal feature, gas pulled out of the Magellanic Clouds by the Milky Way's gravity," McClure-Griffiths said. "Where this gas goes, we'd expect the clouds to follow, at least approximately."

In the distant future, the three galaxies could become one.
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Rogue Stars

2008-02-03T06:29:00.000Z

Rogue Stars - Credit: Andrea Thompson & Live Science

A young star speeding away from the Milky Way is in fact an alien visitor, astronomers have confirmed. The wayward object is one of several rogues that are giving astronomers a glimpse into the volatile nature of our galaxy and others.

Astronomers have found about 10 stars hurtling away from our galaxy, at speeds that exceed its gravitational grasp. While most stars rush through space at speeds on the order of hundreds of kilometers per second, these aptly-named "hypervelocity stars" are rocketing away at least 10 times as fast.

Most of these speedy stars are thought to be exiles from the center of our galaxy, flung out into intergalactic space by the powerful forces of the massive black hole at the center of our galaxy. Their violent creation is giving astronomers insight into the almost impenetrable world at the center of the Milky Way, the mysteries of our nearby galactic neighbours, and the nature of intergalactic space.

Volatile origins
Hypervelocity stars were first theorized to exist in 1988. The theory was that binary star systems at the galaxy's center would occasionally wander too close to the massive black hole looming there, which would disrupt their orbital dance.

While one of the pair was captured by the black hole, the other would be sent rocketing off at an incredible speed.
[+/-] Click here to expand

"That's the only way you can accelerate a star to go thousands of kilometers per second," said astronomer Alcestes Bonanos of the Carnegie Institution for Science, a member of the team that made the discovery of the alien star's origins.

Of the billions of stars in the Milky Way, only a tiny fraction are thought to be shot out from the center like this. This explains why they weren't found until 2005 - because there aren't very many.

Astronomers looked at the spectra of stars at the most outer reaches of the Milky Way and found a few that were going very, very fast, which isn't normal.

By examining the elemental composition of these exiled stars, astronomers can figure out where in the galaxy they came from. With their abundance of heavy metals, most of these stars seem to have come from the center of our galaxy, which tends to spawn more heavy-metal stars.

The galaxy's center is shrouded in gas and dust and normally hard for astronomers to peer into. Gas clouds usually act as excellent stellar nurseries, but the violent tidal forces from the black hole were thought to prevent any nearby stellar births.

The rogue stars seem to contradict that idea, as they seem to have come from the vicinity of the black hole, except for one, which is an alien passerby.

Of these 10 strange stars, one, dubbed HE 0437-5439, seemed a bit stranger than the rest. Based on its current position, the star would have to be 100 million years old to have come from the center of the Milky Way. But it is only 35 million years old.

Bonanos and Lopez-Morales took a closer look at the elemental composition of the star and found that it seemed to be a visitor from our small galactic neighbour, the Large Magellanic Cloud (LMC).

"Stars in the LMC are known to have lower elemental abundances than most stars in our galaxy," Bonanos explained, which seemed to fit HE 0437-5439's make-up.

But while the elemental profile matched, there's one big conundrum: The LMC is not known to have a massive black hole that could eject it. The usual tell-tale signs of a big black hole, such as strong X-ray and radio signals, are missing. Astronomers aren't sure if dwarf galaxies like the LMC have huge black holes in their center, so "this star might be a hint for something important," Bonanos said.

Another strange consequence of these roving stars is the contradiction they provide to the long-held notion that intergalactic space is pretty much empty.

'There seem to be all these stars flying around between galaxies," Bonanos said. If stars are shot out from our galaxy, they are likely propelled from others, she says, though we are unlikely to be able to see them because stars are too hard to individually identify from the distance of most galaxies.

It is predicted that about 1,000 hypervelocity stars have been spit out by the Milky Way's black hole, Bonanos said, though many are still hurtling through the galaxy.

So far all of the hypervelocity stars found are moving away from us, but they could be shot out of the galaxy's center in any direction, up or down from the galactic plane, or even toward us.

But there's no need to worry about a stellar roadrunner knocking into Earth, or any other planet or star. There's a lot of "empty space" in the solar system, so these speeding stars will likely have a clear path out of the neighbourhood.
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Large Mover from The Magellanic Cloud @ Centauri Dreams.
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Young Star Cluster

2008-02-01T12:29:00.000Z

Credit: NASA/CXC/Univ. de Liège/Y. Naze et al

Westerlund 2, a young star cluster with an estimated age of about one or two million years. Until recently little was known about this cluster because it is heavily obscured by dust and gas. However, using infrared and X-ray observations to overcome this obscuration, Westerlund 2 has become regarded as one of the most interesting star clusters in the Milky Way galaxy. It contains some of the hottest, brightest and most massive stars known.

This Chandra image of Westerlund 2 shows low energy X-rays in red, intermediate energy X-rays in green and high energy X-rays in blue. The image shows a very high density of massive stars that are bright in X-rays, plus diffuse X-ray emission.

An incredibly massive double star system called WR20a is visible as the bright yellow point just below and to the right of the cluster's center. This system contains stars with masses of 82 and 83 times that of the Sun. The dense streams of matter steadily ejected by these two massive stars, called stellar winds, collide with each other and produce copious amounts of X-ray emission. This collision is seen at different angles as the stars orbit around each other every 3.7 days. Several other bright X-ray sources may also show evidence for collisions between winds in massive binary systems.

Spitzer Infrared Images of Westerlund 2
RCW 49 is the surrounding HII region around the young stellar cluster Westerlund 2 (Wd2). Because many of the stars in RCW 49 are deeply embedded in plumes of dust, they cannot be seen at visible wavelengths. When viewed with Spitzer's infrared eyes, however, RCW 49 becomes transparent.

Chandra X-ray & Spitzer Infrared Image of Westerlund 2
This coloured Chandra X-ray Observatory image (inset) shows Westerlund 2 in context with the Spitzer infrared observation. ___________________________________________________________
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Cosmic Interactions

2008-01-23T17:47:00.000Z

Credit: ESA Cosmic Interactions NGC 7173, 7174 and 7176

ESO's Very Large Telescope (VLT) images triplet of dancing galaxies intertwined in a cosmic dance.

The three galaxies: NGC 7173 (top), 7174 (bottom right) and 7176 (bottom left), are located 106 million light-years away towards the constellation of Piscis Austrinus (the 'Southern Fish').

NGC 7173 and 7176 are elliptical galaxies, while NGC 7174 is a spiral galaxy with quite disturbed dust lanes and a long, twisted tail.

This seems to indicate that the two bottom galaxies are currently interacting, with NGC 7176 providing fresh material to NGC 7174. Matter present in great quantity around the triplet's members also points to the fact that NGC 7176 and NGC 7173 have interacted in the past.

Astronomers have suggested that The three galaxies will finally merge into a giant 'island universe', tens to hundreds of times as massive as our own Milky Way.

The triplet is part of a so-called 'Compact Group', as compiled by Canadian astronomer Paul Hickson in the early 1980s. The group, which is the 90th entry in the catalogue and is therefore known as HCG 90, actually contains four major members. One of them - NGC 7192 - lies above the trio, outside of this image, and is another peculiar spiral galaxy.

Compact groups are small, relatively isolated, systems of typically four to ten galaxies in close proximity to one another. Another striking example is Robert's Quartet. Compact groups are excellent laboratories for the study of galaxy interactions and their effects, in particular the formation of stars.

As the striking image reveals, there are many other galaxies in the field. Some are distant ones, while others seem to be part of the family. Studies made with other telescopes have indeed revealed that the HCG 90 group contains 16 members, most of them much smaller in size than the four members with an entry in the NGC catalogue.
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Pools of Invisible Matter

2008-01-19T08:42:00.000Z

Super Clusters Credit: Hubble NASA, ESA, C. Heymans (University of British Columbia), M. Gray (University of Nottingham), and the STAGES Collaboration

NASA's Hubble Space Telescope is helping astronomers to dissect one of the largest structures in the universe, in a quest to understand the violent lives of galaxies, and providing indirect evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies.

The images are part of the Space Telescope Abell 901/902 Galaxy Evolution Survey (STAGES), which covers one of the largest patches of sky ever observed by the Hubble telescope.

The area surveyed is so wide that it took 80 Hubble images to cover the entire STAGES field. The new work is led by Meghan Gray of the University of Nottingham in the United Kingdom and Catherine Heymans of the University of British Columbia in Vancouver, along with an international team of scientists.

The Hubble study pinpointed four main areas in the supercluster where dark matter has pooled into dense clumps, totaling 100 trillion times the Sun's mass. These areas match the location of hundreds of old galaxies that have experienced a violent history in their passage from the outskirts of the supercluster into these dense regions. These galaxies make up four separate galaxy clusters.

The dark matter map was constructed by measuring the distorted shapes of over 60,000 faraway galaxies.
[+/-] Click here to expand

To reach Earth, the galaxies' light traveled through the dark matter that surrounds the supercluster galaxies and was bent by the massive gravitational field. Heymans used the observed, subtle distortion of the galaxies' shapes to reconstruct the dark matter distribution in the supercluster using a method called weak gravitational lensing. The dark matter map is 2.5 times sharper than a previous ground-based survey of the supercluster.

On Earth, the pace of quiet country life is vastly different from the hustle of the big city. In the same way, galaxies living lonely isolated lives look very different from those found in the most crowded regions of the universe, like a supercluster. "We've known for a long time that galaxies in crowded environments tend to be older, redder, and rounder than those in the field," Gray said. "Galaxies are continually drawn into larger and larger groups and clusters by the inevitable force of gravity as the universe evolves."

In such busy environments galaxies are subject to a life of violence: high-speed collisions with other galaxies; the stripping away of gas, the fuel supply they use to form new stars; and distortion due to the strong gravitational pull of the underlying invisible dark matter. "Any or all of these effects may play a role in the transformation of galaxies, which is what we're trying to determine," Gray said.

The STAGES survey's simultaneous focus on both the big picture and the details can be likened to studying a big city. "It's as if we're trying to learn everything we can about New York City and New Yorkers," Gray explained. "We're examining large-scale features, like mapping the roads, counting skyscrapers, monitoring traffic. At the same time we're also studying the residents to figure out how the lifestyles of people living downtown differ from those out in the suburbs. But in our case the city is a supercluster, the roads are dark matter, and the people are galaxies."

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Spinning Black Holes

2008-01-16T06:39:00.000Z

Results from NASA's Chandra X-ray Observatory, combined with new theoretical calculations, provide one of the best pieces of evidence yet that many supermassive black holes are spinning extremely rapidly.

The images below show 4 out of the 9 large galaxies included in the Chandra study, each containing a supermassive black hole in its center.

The Chandra images show pairs of huge bubbles, or cavities, in the hot gaseous atmospheres of the galaxies, created in each case by jets produced by a central supermassive black hole. Studying these cavities allows the power output of the jets to be calculated. This sets constraints on the spin of the black holes when combined with theoretical models.

The Chandra images were also used to estimate how much fuel is available for each supermassive black hole, using a simple model for the way matter falls towards such an object. The artist's impression on the right side of the main graphic shows gas within a "sphere of influence" falling straight inwards towards a black hole before joining a rapidly spinning disk of matter near the center.

Most of the material in this disk is swallowed by the black hole, but some of it is swept outwards in jets (coloured blue) by quickly spinning magnetic fields close to the black hole.
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The Moth

2008-01-13T09:36:00.000Z

The Moth. Credit: Hubble

The object resembling a giant moth floating in space, with a wingspan of about 22 billion miles, is actually a dust disk encircling the nearby, young star HD 61005. Dubbed "The Moth" - its shape is produced by starlight scattering off dust.

Dust disks around roughly 100-million-year-old stars like HD 61005 are typically flat, pancake-shaped structures where planets can form. But images taken with NASA's Hubble Space Telescope of "The Moth" are showing that some disks sport surprising shapes.

"We think HD 61005 is plowing through a local patch of higher-density gas in the interstellar medium, causing material within HD 61005's disk to be swept behind the star." "What effect this might have on the disk, and any planets forming within it, is unknown," said senior research scientist Dean Hines of the Space Science Institute in Corrales, New Mexico, and a member of the Hubble team that discovered the disk.

Hines called this possible collision "unusual, because we don't expect very much interstellar material to be in the solar neighbourhood. That's because the area through which our Sun is moving was evacuated within the past few million years by at least one supernova, the explosion of a massive star. Yet, here's evidence of dense material that's very close, only 100 light-years away."

Astronomers have found evidence that the environment in which a star forms influences its prospects for planet formation. Hubble has actually seen that young planet-forming disks can be affected directly by their environment.

The harsh stellar radiation from the Trapezium stars in the Orion Nebula has altered some disks. It is unclear, however, what effect passage through a cloud similar to the one in which HD 61005 finds itself would have on planet formation. Researchers have speculated that passage through dense regions of the interstellar medium could impact the atmospheres of evolving planets.
[+/-] Click here to expand

The Moth is part of a survey of Sun-like stars that Hines and collaborators observed with Hubble's Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) and NASA's Spitzer Space Telescope to study the formation and evolution of planetary systems. Under the lead of Michael Meyer of the University of Arizona in Tucson, the team initially used Spitzer to look for heat radiation—the tell-tale sign of dust warmed by the star—to identify interesting star systems.

Hines then teamed with Glenn Schneider of the University of Arizona to use Hubble's high- contrast imaging capability of the NICMOS coronagraph to image these disks and reveal where the dust detected by Spitzer resides. The NICMOS coronagraph blocked out the starlight so that astronomers could see details in the surrounding disk.

"These symbiotic capabilities, uniquely implemented in NASA's Great Observatories, provide astronomers with the powerful observational tools to study the circumstellar environments of potentially planet-forming systems," Schneider said.

Added Meyer: "Combining observations from these two spacecraft gives us information about the composition of the dust grains, whether they're icy or sandy, or whether they're like the sooty smoke particles rising from a chimney. The composition and sizes of the dust can tell us a lot about the dynamics and evolution of a solar system. In our solar system, for example, astronomers have evidence of rocks smashing into each other and generating dust, as in the asteroid and Kuiper belts. We're seeing these same processes unfold in other planetary systems."

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Orphaned Star Clusters

2008-01-08T19:21:00.000Z

Hubble: Orphaned Star Clusters - Click on Image to Enlarge

[LEFT] A GALEX ultraviolet image of the interacting galaxies M81 and M82, which lie 12 million light-years away in the constellation Ursa Major. The gravity from each galaxy dramatically affected the other during their last close encounter, 200 million years ago.

Gas density waves rippling around M81 make it a grand design spiral. M82 is undergoing a starburst at its core, creating glowing fingers of hydrogen.

[RIGHT] A Hubble Space Telescope visible light image of bright blue star clusters found along a wispy bridge of gas that was tidally stretched between the two galaxies, and a third companion galaxy not seen in this picture. This is not the place astronomers expect to find star clusters because the density of gas is so low. Turbulence in the gas may have enhanced the density locally to trigger starbirth.

The "blue blobs" are clumped together in a structure called Arp's Loop. Hubble reveals the clusters contain the equivalent of five Orion Nebulae. A Hubble plot of the stellar population in the clusters yields an age of approximately 200 million years, which coincides with the epoch of the collision.
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The Three Magi

2008-01-06T15:15:00.000Z

The Three Magi

Till the present, from Ancient Times,
Since Man became Man, there have been stargazers
till the present, from Ancient Times.

Everyday we can see further and further, as we unravel
the inmensity of this Universe and the great beyond.
Everyday we unravel & reveal new secrets of what we see
the beauty of life, and all that in an instant came to be.

So here's many more best wishes from me to thee.
May this year be filled with much joy & many gifts.
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35th Carnival of Space from Music of the Spheres
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The Magic Circle

2008-01-01T04:04:00.000Z

Magic Circle, by John William Waterhouse (1886)

Ceating a magic circle is known as casting a circle, circle casting. There are many different techniques for casting a circle.

The common feature of these practices is that a barrier of energy is traced in a circle around the working area. Some traditions say that one must go around the circle deosil three times. There are also various starting points based on cardinal directions. A typical size for a circle is nine feet and an individual's circle is five feet in diameter, though the size can vary depending on the purpose of the circle, and the preference of the caster.

Some practitioners choose to mark the physical boundary of their circle, either before or prior to the actual casting. This can be done using a cord, a chalk line, a line drawn in the soil, or small objects such as stones.

Some practitioners mark the four cardinal points with candles, either white, or of colours representative of the elements: North: green for the element of Earth; East: yellow for the element of Air; South: red for the element of Fire; West: blue for the element of Water.

Though some practitioners, associate North with Air and East with Earth. Generally, as with most magical practices, an incantation is recited stating the purpose and nature of the circle.

Traditionally, circles were used by ritual magicians to form a protective barrier between themselves and what they summoned. Nowadays, the circle has taken the more benign function of containing the energy raised during the ritual that follows.

As more and more energy is raised from chanting and dancing the energy becomes more concentrated. After the circle has been cast it is believed that it forms a sphere of energy, which intersects the ground at its equator. This shouldn't be confused with the cone of power, a method of raising energy.

Circles can also be used as barriers for non-magical work such as meditation. The barrier is fragile and sensitive to things passing through it. Leaving or passing through the circle often weakens or dispels the barrier. This is referred to as "breaking the circle". It is generally advised that practitioners don't leave the circle unless absolutely necessary.

The Magic Circle is a British organisation dedicated to magic. Its headquarters are in London, and professional magicians who want to join need to first demonstrate their skills to existing members. There are currently approximately 1500 members (including Charles, Prince of Wales) in 41 countries.

The Magic Circle was founded in 1905 after a meeting of 23 amateur and professional magicians at London's Pinoli's Restaurant. The first official meeting was held at The Green Man public house in Soho, but meetings were later held in a room at St. George's Hall in Langham Place. The current president (2007) is Alan Shaxon whose term of office will end in September 2008.

The motto of the society is the Latin indocilis privata loqui, which may be roughly translated as "not apt to disclose secrets"; Members give their word not to wilfully disclose magic secrets other than to bona fide students of magic. Anyone breaking this or any other rule may be subject to expulsion from the society.

Since 1998, The Magic Circle Headquarters building in central London has also been available for use as a venue for meetings and corporate entertainment. It has been voted best unusual venue by the hospitality industry. A virtual tour of the building and information are available online.

Happy New Year!
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Pulsed Heartbeat Star

2007-12-28T00:00:00.000Z

XMM-Newton has detected periodic X-ray emission, or the pulsed heartbeat of a new type of star. Collecting the X-rays from the so-called rotating radio transient has confirmed the nature of the underlying celestial object and given astronomers a new insight into these exotic objects. The observations were made using XMM-Newton's European Photon Imaging Camera (EPIC), which targeted the celestial object RRAT J1819-1458. Astronomers observed the object for around 12 hours and detected pulsations in the X-ray data that show the source to be rotating once every 4.26 seconds.

Previously, astronomers had only seen radio outbursts from this object. It erupts every three minutes or so with a brief burst of radio emission lasting just 3 milliseconds. Such behaviour defines the object as a rotating radio transient.
[+/-] Click here to expand

The RRATs were announced in February 2006. Eleven objects were found using the Parkes radio telescope. Astronomers suspected that RRATs were neutron stars, the compact remnants of dead stars made of neutrons and measuring just 10-12 km across yet containing more matter than the Sun. They are therefore extremely dense. Most observed neutron stars are radio pulsars; rotating quickly and sweeping lighthouse beams of radiation across space that make them appear to pulsate. The RRATs, however, were only detected through their radio bursts.

The new XMM-Newton observations show that periodic emission, linked to the object's rotation, can be detected in X-rays. "It is now definite that RRATs are rotating neutron stars as we can see the 4.26-second rotation period of the RRAT in the X-ray data," says Maura McLaughlin, West Virginia University, USA, who took the lead in the research.

In addition to the identification of the underlying celestial object from the discovery of the X-ray pulsations, XMM-Newton also revealed another facet of the RRAT's behaviour. Something appears to be absorbing certain frequencies of the X-rays after they are emitted from the surface of the neutron star.

The absorption could either be happening in an atmosphere of gases surrounding the neutron star or by particles trapped in the neutron star's magnetic field. If the second reason is the cause of the absorption, it would indicate that the magnetic field of this RRAT is strong. "We can't say for sure where the absorption is coming from with these observations," says Nanda Rea, University of Amsterdam, Netherlands. She estimates that an observation twice as long would collect enough data to determine where the absorption is taking place.

She also hopes to follow-up this observation by targeting other RRATs. Before that can happen, however, the team must refine the positions they have for these objects. To do this, they continue to observe the RRATs with radio telescopes across the world, timing the outbursts. From careful measurements of the arrival times of the bursts over the course of the year, their positions in the sky can be determined more accurately. Once these locations are known, X-ray telescopes can be pointed in their direction.

Since the original discovery of 11 RRATs, McLaughlin's team has found an additional 10. This indicates that they may form a substantial population in the Milky Way, with over 100,000 of them dotted around our galaxy.

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The Cosmic Bird

2007-12-23T01:35:00.000Z

Credit: ESO Press Photo 54a/07

Using ESO's Very Large Telescope, an international team of astronomers has discovered a stunning rare case of a triple merger of galaxies. This system, which astronomers have dubbed 'The Bird' - composed of two massive spiral galaxies and a third irregular galaxy.

The galaxy ESO 593-IG 008, or IRAS 19115-2124, was previously merely known as an interacting pair of galaxies at a distance of 650 million light-years. But surprises were revealed by observations made with the NACO instrument attached to ESO's VLT, which peered through the all-pervasive dust clouds, using adaptive optics to resolve the finest details.

Underneath the chaotic appearance of the optical Hubble images - retrieved from the Hubble Space Telescope archive - the NACO images show two unmistakable galaxies, one a barred spiral while the other is more irregular.

The surprise lay in the clear identification of a third, clearly separate component, an irregular, yet fairly massive galaxy that seems to be forming stars at a frantic rate.

Because of the resemblance of the system to a bird, the object was dubbed as such, with the 'head' being the third component, and the 'heart' and 'body' making the two major galaxy nuclei in-between of tidal tails, the 'wings'. The latter extend more than 100,000 light-years, or the size of our own Milky Way.

Subsequent optical spectroscopy with the new Southern African Large Telescope, and archive mid-infrared data from the NASA Spitzer space observatory, confirmed the separate nature of the 'head', but also added further surprises. The 'head' and major parts of the 'Bird' are moving apart at more than 400 km/s (1.4 million km/h!). Observing such high velocities is very rare in merging galaxies. Also, the 'head' appears to be the major source of infrared luminosity in the system, though it is the smallest of the three galaxies.

The 'head' is forming stars violently, at a rate of nearly 200 solar masses per year, while the other two galaxies appear to be at a more quiescent epoch of their interaction-induced star formation history.

The 'Bird' belongs to the family of luminous infrared galaxies, with an infrared luminosity nearly one thousand billion times that of the Sun. This family of galaxies has long been thought to signpost important events in galaxy evolution, such as mergers of galaxies, which in turn trigger bursts of star formation, and may eventually lead to the formation of a single elliptical galaxy.
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Is it all an illusion or light from a beam
Reality is relative, and always supreme
though for a moment it may not so seem
May the new year fulfill your every dream
Hubblesite presents - Striking Galaxy Encounters
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Merry Xmas to You All

2007-12-20T00:08:00.000Z

Early stages of Solar System & Planet formation
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When the Solar System Went from Dust to Mountains
Galaxy Has 1,000 Times Our Rate of Star Formation
Supernova Generates Enough Dust for 10,000 Earths from Universe Today
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Death Star Galaxy

2007-12-17T19:10:00.000Z

Credit: NASA, ESA, and D. Evans (Harvard-Smithsonian Center for Astrophysics)

A powerful jet from a supermassive black hole is blasting a nearby galaxy, according to new data from NASA observatories. This never-before witnessed galactic violence may have a profound effect on planets in the jet's path and trigger a burst of star formation in its destructive wake.

Known as 3C 321, the system contains two galaxies in orbit around each other. Data from NASA's Chandra X-ray Observatory show both galaxies contain supermassive black holes at their centers, but the larger galaxy has a jet emanating from the vicinity of its black hole. The smaller galaxy apparently has swung into the path of this jet.

This "death star galaxy" was discovered through the combined efforts of both space and ground-based telescopes. NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope were part of the effort. The Very Large Array (VLA) in Socorro, N.M., and the Multi-Element Radio Linked Interferometer Network (MERLIN) telescopes in the United Kingdom also were needed for the finding.

Jets from supermassive black holes produce high amounts of radiation, especially high-energy X-rays and gamma-rays, which can be lethal in large quantities. The combined effects of this radiation and particles traveling at almost the speed of light could severely damage the atmospheres of planets lying in the path of the jet. For example, protective layers of ozone in the upper atmosphere of planets could be destroyed.

Jets produced by supermassive black holes transport enormous amounts of energy far from the black holes and enable them to affect matter on scales vastly larger than the size of the black hole. Learning more about jets is a key goal for astrophysical research.

The effect of the jet on the companion galaxy is likely to be substantial, because the galaxies in 3C 321 are extremely close at a distance of only about 20,000 light-years apart, approximately the same distance as Earth is from the center of the Milky Way galaxy.

A bright spot in the VLA and MERLIN images shows where the jet has struck the side of the galaxy, dissipating some of the jet's energy. The collision disrupted and deflected the jet.

Another unique aspect of the discovery in 3C 321 is how relatively short-lived this event is on a cosmic time scale. Features seen in the VLA and Chandra images indicate that the jet began impacting the galaxy about one million years ago, a small fraction of the system's lifetime. This means that such an alignment is quite rare in the nearby universe, making 3C 321 an important opportunity to study such a phenomenon.

It is possible the event is not all bad news for the galaxy being struck by the jet. The massive influx of energy and radiation from the jet could induce the formation of large numbers of stars and planets after its initial wake of destruction is complete.

For more images and information about 3C 321, visit:
http://chandra.harvard.edu
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Mountains of Creation

2007-12-15T11:26:00.000Z

Mountains of Creation

This fantastic skyscape lies at the eastern edge of giant stellar nursery W5, about 7,000 light-years away in the constellation Cassiopeia.

An infrared view from the Spitzer Space Telescope, it features interstellar clouds of cold gas and dust sculpted by winds and radiation from a hot, massive star just outside the picture (above and to the right).

Still swaddled within the cosmic clouds, newborn stars are revealed by Spitzer, their formation also triggered by the massive star. Fittingly dubbed "Mountains of Creation", these interstellar clouds are about 10 times the size of the analogous Pillars of Creation in M16, made famous in a 1995 Hubble Space Telescope view.

W5 is also known as IC 1848 and together with IC 1805 it is part of a complex region popularly dubbed the Heart and Soul Nebulae. The Spitzer image spans about 70 light-years.

Credit: Lori Allen (Harvard-Smithsonian CfA) et al., JPL-Caltech, NASA
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Celestial Magnetic Ropes

2007-12-12T15:08:00.000Z

NASA satellites have uncovered giant 'magnetic ropes' linking the Earth's atmosphere to the Sun. These channel solar energy to create the spectacular northern and southern lights.

"The satellites have found evidence of magnetic ropes connecting Earth's upper atmosphere directly to the Sun," said David Sibeck, project scientist at NASA's Goddard Space Flight centre in Maryland.

"We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras," he told the annual meeting of the American Geophysical Union in San Francisco.

Enormous burst of energy
The discovery is among a series of revelations made by the U.S. space agency's Time History of Events and Macroscale Interactions during Substorms mission (THEMIS) launched earlier this year.

A 'magnetic rope' is a twisted bundle of magnetic fields much like a rope made of hemp, and although previous spacecraft have seen glimpses of them, none had been able to map their structure. But the THEMIS's five identical micro-satellites could.

THEMIS encountered its first magnetic rope on May 20. It was very large, about as wide as Earth, and located approximately 65,000 km above Earth's surface in a region called the magnetopause.

This is the region where solar wind hurtles into the Earth's magnetic fields, and magnetic ropes are formed and unfurled in just a few minutes allowing solar wind to be briefly conducted along them.

This enormous burst of energy helps explain the phenomenon of aurora borealis (and its southern hemisphere equivalent, the aurora australis) also known as substorms, said Sibeck.

A substorm, which erupted over Alaska and Canada on March 23, provided a stunning show of auroras for more than two hours. They were photographed from below while satellites measured the particles and fields above, and showed a series of 10-minute outbursts.

Speedy substorms
The mission's principal investigator Vassilis Angelopoulos said the storm behaved very unexpectedly. "The auroras surged westward twice as fast as anyone thought possible, crossing 15 degrees of longitude in less than one minute… The storm traversed an entire polar time zone, or 400 miles, in 60 seconds flat."

The total energy required for such a two-hour show was about five hundred thousand billion Joules, or the equivalent of a 5.5 magnitude earthquake, Angelopoulos said.

The THEMIS mission also witnessed small explosions on the outskirts of the Earth's magnetic field in an area known as the bow shock.

"The bow shock is like the bow wave in front of a boat," said Sibeck. "It is where the solar wind first feels the effects of Earth's magnetic field. Sometimes a burst of electrical current within the solar wind will hit the bow shock and 'Bang!' we get an explosion."

THEMIS is a two-year mission being coordinated by the University of Berkeley in California, with several countries contributing.

Every four days the five THEMIS satellites line up along the Earth's magnetic field to follow disturbances in the magnetopause region. This allows the storms to be observed from five different angles simultaneously, helping scientists to learn about the origins of the storms and their evolutions.
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Saturn Ringed by Electric Doughnut by Dave Mosher @ LiveScience
Part of Milky Way rotates in Opposite direction - from SPACEcom
Ultra High Energy Cosmic Rays by Charles Daney @ Science & Reason
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A Million Light Years

2007-12-08T07:14:00.000Z

An intergalactic particle beam stretching for more than a million light years is the longest ever seen. According to the team that discovered this record breaker, it could help reveal how such jets of matter bind themselves together.

Jets are seen all over the cosmos emerging out of many different types of object, including stars that are just beginning to form. The most powerful ones come from the cores of active galaxies, where gas falling towards a giant black hole generates a mixture of heat, high-energy particles and magnetic fields. In some cases, these elements combine to spit out narrow columns of hot gas laced with high-energy particles, which drill though the galaxy and on out into space.

The latest discovery emerges from a large elliptical galaxy called CGCG 049-033, which is about 600 million light years away. A team led by Joydeep Bagchi of Pune University in Maharashtra, India, noticed emission from this galaxy during a broad search for radio sources, and then took a closer look using the Giant Metrewave Radio Telescope near Pune and the 100-metre Effelsberg radio dish in Germany.

The jet they saw is nearly 1.5 million light years long, twice the length of the previous record holder. If this jet sprang instead from the centre of the Milky Way, it would loom over us like a skyscraper and would stretch halfway to the Andromeda galaxy.

It is unusual in other ways too. Jets usually come in fairly well-matched pairs, pointing in opposite directions. The new jet's counterpart, however, appears much shorter. That could be because the apparently shorter jet is pointing away from us - so light from its far end might not have had time to reach us yet.

Interestingly, the radio waves emitted by the newly discovered jet are strongly polarised, revealing a powerful magnetic field wrapped around the jet. "I was very surprised to find such a strong and regular magnetic field," said team member Marita Krause from the University of Bonn in Germany.

It may be that the magnetic field acts as a containing sheath, preventing the high-pressure gas in the jet from dispersing. That could explain why this jet is so long. A somewhat weaker version of this magnetic containment field might help hold jets together around other types of astronomical objects.

The team plans to get an even more detailed picture of the jet and its magnetic fields using the Very Large Array radio observatory in New Mexico, US.
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The Evolution of Binary Stars from News Account @ Scientific Blogging
When Do Gas Giants Reach The Point Of No Return? from Science Daily
Odd Little Star Has Magnetic Personality from the Gemini Observatory
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White Dwarfs Get A Kick

2007-12-05T11:54:00.000Z

NGC 6397. Click on Image to Enlarge

These images show young and old white dwarf stars — the burned-out relics of normal stars — in the ancient globular star cluster NGC 6397.

The image at left, taken by a ground-based telescope, shows the dense swarm of hundreds of thousands of stars that make up the globular cluster. The white box outlines the location of the observations made by NASA's Hubble Space Telescope.

The image at top, right, taken by Hubble's Advanced Camera for Surveys, reveals young white dwarfs less than 800 million years old and older white dwarfs between 1.4 and 3.5 billion years old. The photo shows 12 of the 84 white dwarfs in the Hubble study. The blue squares pinpoint the young white dwarfs; the red circles outline the older white dwarfs. The Hubble researchers distinguished the younger from the older white dwarfs based on their colour and brightness. The younger white dwarfs are hotter and therefore bluer and brighter than the older ones.

The astronomers were surprised to find young white dwarfs far away from the cluster's core. They had assumed that the youngsters would reside at the center and migrate over time to the cluster's outskirts. The astronomers proposed that the cluster stars that burn out as white dwarfs are given a boost that propels them to the edge of the cluster.

Close-up images of the white dwarfs are shown at bottom, right. The blue boxes represent the young white dwarfs; the red boxes indicate the older white dwarfs.

Read more @ How White Dwarfs Get Their 'Kicks' from Hubble
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White Dwarfs Rocket Away When They're Born @ Universe Today
First Findings On Key Astrophysics Problem - from Science Daily
Radiation Flashes May Help Crack Cosmic Mystery from Science Daily
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Dark Stars of Creation (?)

2007-12-03T18:39:00.000Z

The universe's first stars may have been bloated behemoths powered by dark matter, suggests a speculative, new study. These 'dark stars' might have delayed the creation of heavy elements, which make up everything from planets to people, as well as cosmic reionisation, which made the universe transparent to light billions of years ago.

Theorists believe the first stars formed in cradles of dark matter, condensing from clouds of gas until their cores became so dense that nuclear fusion ignited, preventing the cores from collapsing further.

But previous research did not consider how the dark matter cradles themselves might affect star formation. When they accounted for dark matter, they discovered it could have had a profound influence on the first stars.

Just what that effect is is still unclear, since no one knows what dark matter is – astronomers merely detect its gravitational pull on normal matter. But if it is made of weakly interacting massive particles, or WIMPs, as many scientists believe, Spolyar and his colleagues say it could drastically alter the physics of the earliest stars.

They used a candidate WIMP called a neutralino in their calculations and found that as a primordial gas cloud contracted, it reached a threshold density in which the dark matter particles swaddling it began to interact with each other. They annihilated on contact, producing particles such as electrons as well as photons of light that then deposited energy into the cloud.
[+/-] Click here to expand

This could heat up the cloud so much that it would stop contracting, so that it was supported by the annihilation of dark matter rather than by nuclear fusion, like normal stars. Such a 'dark star' would be about as massive as the Sun and would glow at infrared wavelengths. But it would be much larger – depending on the mass of the neutralino used, the star could span anywhere from the distance between the Sun and Uranus in our solar system to nearly 60 times that size.

"To call it a dark star is a bit of a misnomer – it simply has a different source of internal energy to support the star against gravity," says Volker Bromm of the University of Texas in Austin, US, an expert on the universe's first stars who is not a member of the study. "It would be a ball of gas that would have a reddish glow."

Could any of these stars still survive today? Possibly, depending on the neutralino mass, say the researchers. "They could be flying around our galaxy, in which case, the very first generation of stars in the universe (population III' stars) would have been very different from that previously thought", the team says.

Nearly all of the elements in the universe aside from hydrogen and helium were forged inside stars, and "the first stars are the first step in that process". If the first stars were dark, "there could be a major delay or even a stopping of this process", says team member Freese.

"It may turn out that the early star formation and consequently the synthesis of elements went differently than we thought," comments Igor Moskalenko of Stanford University in California, US. "If so, we have evidence of the dark matter presence literally in every cell of our body."

Other 'pop III' stars – which formed inside early galaxies rather than isolated dark matter cradles – would thus have been responsible for seeding the universe with its first heavy elements.

That suggests that heavy elements may not be spread evenly throughout space, since the stars in early galaxies would have enriched their surroundings in these elements and left voids of relatively empty space unenriched, says Bromm. If astronomers ever find a truly primordial cloud of gas in the universe, then it might hint that the first stars were dark.

Similarly, the first stars are thought to have helped ionise the universe within a few hundred million years after the big bang, making it transparent to ultraviolet light. (This phenomenon is actually referred to as 'reionisation', since the universe was a scalding soup of charged particles immediately after the big bang. It then cooled down enough for ions to coalesce into neutral atoms after 370,000 years or so.)

If the first stars were dark, then that suggests the stars in early dwarf galaxies would have been responsible for reionising the universe, says Bromm.

"Another thing that's exciting to me is that we may have a new type of star and we can go look for these things," says Freese. Neutrinos produced by the annihilation of dark matter in the stars might turn up in detectors such as AMANDA and IceCube at the South Pole, and gamma-ray photons produced in the same process could be picked up by NASA's GLAST spacecraft, due to launch in mid-2008.

Bromm says the research is quite speculative, since there are "incredibly many degrees of freedom when it comes to the properties of dark matter". But he adds that the work helps to bridge the gap between studies of dark matter on a particle physics scale and its effect on astronomical objects.

This paper is one of the first in this line of convergence between micro and macro physics.

Universe's first stars may have been dark by Maggie Mckee @ NewScientistSpace

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Out Among the Dark Stars - by Paul Gilster @ Centauri Dreams
Were The First Stars Dark? - News Account @ Scientific Blogging
Invisible Matter Loses Cosmic Battle by Jeanna Bryner @ LiveScience
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Million Degree Plasma

2007-12-01T11:26:00.000Z

A million-degree plasma cloud in the Orion Nebula.

The emission coloured in blue shows X-ray emission from a hot plasma cloud in the extended regions of the Orion Nebula, detected by the XMM-Newton satellite. The background image has been recorded by the Spitzer Space Telescope in the infrared, showing emission from cool dust.

Stars in our galaxy may often pump out waves of million-degree gas that make surrounding nebulas glow with x-rays.

Astrophysicists focused on the Orion Nebula, a cloud of dense and turbulent gas visible to the naked eye in the night sky, right below the belt of the constellation Orion. Four extremely bright and massive stars, called the Trapezium, light up the nebula.

One stretch of the nebula, about 10 light-years wide, glows with x-rays. This glow apparently results from super-heated gas-some 1.7 million to 2.1 million degree Celsius hot-that pervades the cloud.

Often such vast expanses of super-heated gas come from exploded stars called supernovas or from large collections of very massive stars. Now an international research team using the XMM-Newton space observatory finds this gas seems to flow from just one bright, young, massive star in the Trapezium.

It is believed that our sun was born in an Orion-like environment.

Researchers now hope to understand how these x-ray glows might alter the environments in which planetary systems form, possibly even influencing the very chemistry of worlds.
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Huge Stars Seen as Source of Glowing Gas from LiveScience
Star forming region Theta1 Orionis C from Scientific Blogging
ESA's XMM-Newton X-ray observatory images of Orion from ESA
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3 million miles per hour

2007-11-28T18:30:00.000Z

Click on Image to Enlarge.

This graphic shows a wide-field view of the Puppis A supernova remnant along with a close-up image of the neutron star, known as RX J0822-4300. The larger field-of-view is a composite of X-ray data from the ROSAT satellite (pink) and optical data (purple), from the Cerro Tololo Inter-American Observatory 0.9-meter telescope, which highlights oxygen emission. Astronomers think Puppis A was created when a massive star ended its life in a supernova explosion about 3,700 years ago, forming an incredibly dense object called a neutron star and releasing debris into space.

The neutron star was ejected by the explosion. The inset box shows two observations of this neutron star obtained with the Chandra X-ray Observatory over the span of five years, between December 1999 and April 2005. By combining how far it has moved across the sky with its distance from Earth, astronomers determined the cosmic cannonball is moving at over 3 million miles per hour, one of the fastest moving stars ever observed. At this rate, RX J0822-4300 is destined to escape from the Milky Way after millions of years, even though it has only traveled about 20 light years so far.

The results from this study suggest the supernova explosion was lop-sided, kicking the neutron star in one direction and much of the debris from the explosion in the other. The estimated location of the explosion is shown in the above composite image. The direction of motion of the cannonball, shown by an arrow, is in the opposite direction to the overall motion of the oxygen debris, seen in the upper left. The arrows show the estimated motion over the next 1,000 years. The oxygen clumps are believed to be massive enough so that momentum is conserved in the aftermath of the explosion.

Credit: Chandra: NASA/CXC/Middlebury College/F.Winkler et al.; ROSAT: NASA/GSFC/S.Snowden et al.; Optical: NOAO/CTIO/Middlebury College/F.Winkler et al.
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Star cluster's extreme speed puzzles astronomers from New Scientist
ESO's VLT takes the search for young galaxies to new limits from ESO
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The Closest Galaxy

2007-11-24T11:33:00.001Z

The Closest Galaxy: Canis Major Dwarf. - Illustration Credit & Copyright: R. Ibata (Strasbourg Observatory, ULP) et al., 2MASS, NASA

What is the closest galaxy to the Milky Way? The new answer to this old question is the Canis Major dwarf galaxy. For many years astronomers thought the Large Magellan Cloud (LMC) was closest, but its title was supplanted in 1994 by the Sagittarius dwarf galaxy.

Recent measurements indicate that the Canis Major dwarf is only 42,000 light years from the Galactic center, about three quarters of the distance to the Sagittarius dwarf and a quarter of the distance to the LMC. The discovery was made in data from the 2MASS-sky survey, where infrared light allows a better view through our optically opaque Galactic plane.

The labeled illustration above shows the location of the newly discovered Canis Major dwarf and its associated tidal stream of material in relation to our Milky Way Galaxy. The Canis Major dwarf and other satellite galaxies are slowly being gravitationally ripped apart as they travel around and through our Galaxy
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Astronomers Discover Stars With Carbon Atmospheres from Space Daily
New Type of Dying Star Discovered by Charles Q Choi @ Space dot com
Astronomers Observe Acidic Milky Way Galaxies from Science Daily
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LIGO scanning the skies

2007-11-21T12:24:00.001Z

Searching for one of Einstein's greatest predictions:

Gravitational waves are produced when massive objects in space move violently. The waves carry the imprint of the events that cause them. Scientists already have indirect evidence that gravitational waves exist, but have not directly detected them.

The Laser Interferometer Gravitational-wave Observatory, or LIGO, consists of detectors at two U.S. sites managed by the California Institute of Technology (Caltech) and Massachusetts Institute of Technology (MIT).

The LIGO observatories use lasers to accurately monitor the distance between a central station and mirrors suspended three miles away along perpendicular arms. When a gravitational wave, a traveling ripple in space-time, passes by, the mirror in one arm will move closer to the central station, while the other mirror will move away.

The change in distance caused by stretching and squeezing is what LIGO is designed to measure, says Alan Wiseman - associate professor @ UWM's Center for Cosmology and Gravitation.

Those changes will be inconceivably tiny. LIGO can record distortions at a scale so small, it is comparable in distance to a thousandth of the size of an atomic nucleus.

LIGO records a series of numbers - lots of them - and feeds them to several supercomputer clusters around the country, including UWM's Nemo cluster.

The computer's job is to sort out the numerical patterns representing gravitational waves buried in ambient noise produced by lots of other vibrations - from internal vibrations of the equipment itself, to magnetic fluctuations from lightning storms, to seismic vibrations from trains rolling along the tracks a few miles from the observatory, or from earthquakes on the other side of the world.

There are thousands or even millions of different signals that could be emitted from space. So you have to take each segment of data individually. Nemo performs many billions of calculations per second in its search for these signals.

The strings of numbers from LIGO are like tracks on a compact disk. Once detected, gravitational-wave signals can be converted into sound. Scientists have already simulated, based on mathematical predictions, what certain events in space will sound like.

When two black holes are merging, for example, you might expect to hear a "chirp" that represents the spiraling together of the black holes just before they collide. "The spiral can go on for thousands of years," says Brady, a UWM professor of physics. "The sound is the identifying signal of the last few seconds of the process!"

Gravitational waves may hold secrets to the nature of black holes, the unknown properties of nuclear material, and maybe even how the universe began.

"We've only been able to find out about the universe since it became cool. But with gravitational waves, we'll see the universe when it was much younger -- and hotter." "I think we're in for a surprise," says Siemens from UWM's Center for Cosmology and Gravitation. "We have all these ideas about what we think we will find, but it could be something completely different."
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Can 3D movies like Beowulf save the World of Cinema
What Space Telescopes of Tomorrow Will See from LiveScience
Surrogate Memory - Back Up Your Brain from The Galactic Emporium
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Bustling Hub of Star Formation

2007-11-15T22:27:00.000Z

Credit: X-ray: NASA/CXC/CfA/S.Wolk et al;
Optical: NSF/AURA/WIYN/Univ. of Alaska/T.A.Rector

NGC 281 is a bustling hub of star formation about 10,000 light years away in the Constellation of Cassiopeia. This composite image of optical and X-ray emission includes regions where new stars are forming and older regions containing stars about 3 million years old.

The optical data (seen in red, orange, and yellow) show a small open cluster of stars, large lanes of obscuring gas and dust, and dense knots where stars may still be forming. The X-ray data (purple), based on a Chandra observation lasting more than a day, shows a different view. More than 300 individual X-ray sources are seen, most of them associated with IC 1590, the central cluster.

The edge-on aspect of NGC 281 allows scientists to study the effects of powerful X-rays on the gas in the region, the raw material for star formation.

A second group of X-ray sources is seen on either side of a dense molecular cloud, known as NGC 281 West, a cool cloud of dust grains and gas, much of which is in the form of molecules. The bulk of the sources around the molecular cloud are coincident with emission from polycyclic aromatic hydrocarbons, a family of organic molecules containing carbon and hydrogen.

There also appears to be cool diffuse gas associated with IC 1590 that extends toward NGC 281 West.

The X-ray spectrum of this region shows that the gas is a few million degrees and contains significant amounts of magnesium, sulfur and silicon. The presence of these elements suggests that supernova recently went off in that area.

More Images of NGC 281 from Chandra
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Hubble's Island Universes: Watching Galaxies Grow Old Gracefully
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Highest-Energy Cosmic Rays

2007-11-12T19:11:00.000Z

Active Galactic Nuclei (AGN) are found at the hearts of some galaxies and are thought to be powered by supermassive black holes that are devouring large amounts of matter.

They have long been considered sites where high-energy particle production might take place. They swallow gas, dust and other matter from their host galaxies and spew out particles and energy.

While most galaxies have black holes at their centre, only a fraction of all galaxies have an AGN. The exact mechanism of how AGNs can accelerate particles to energies 100 million times higher than the most powerful particle accelerator on Earth is still a mystery.
[+/-] Click here to expand

Cosmic rays are protons and atomic nuclei that travel across the universe at close to the speed of light. When these particles smash into the upper atmosphere of our planet, they create a cascade of secondary particles called an air shower that can spread across 40 or more square kilometres as they reach the Earth’s surface.

Professor Subir Sarkar of the Physics Department at Oxford University, a member of the Auger Collaboration, said: ‘The Auger data indicates that the sources of ultrahigh energy cosmic rays are associated with nearby 'active galaxies' which harbour supermassive black holes that are gobbling up stellar matter and ejecting huge jets of plasma. Our own galaxy too has such a black hole at its centre but, fortunately for us, it is not 'feeding' at the moment!’

The Pierre Auger Observatory records cosmic ray showers through an array of 1,600 particle detectors placed 1.5 kms apart in a grid spread across 3,000 square kms. Twenty-four specially designed telescopes record the emission of fluorescence light from the air shower. The combination of particle detectors and fluorescence telescopes provides an exceptionally powerful instrument for this research.

While the observatory has recorded almost a million cosmic-ray showers, only the rare, highest-energy cosmic rays can be linked to their sources with sufficient precision. Auger scientists so far have recorded 81 cosmic rays with energy above 4 x1019 electron volts, or 40 EeV. This is the largest number of cosmic rays with energy above 40 EeV recorded by any observatory.

At these ultra-high energies, the uncertainty in the direction from which the cosmic ray arrived is only a few degrees, allowing scientists to determine the location of the particle’s cosmic source.

The Auger collaboration discovered that the 27 highest-energy events, with energy above 57 EeV, do not come equally from all directions. Comparing the clustering of these events with the known locations of 381 Active Galactic Nuclei, the collaboration found that most of these events correlated well with the locations of AGNs in some nearby galaxies, such as Centaurus A.

Click Image to Enlarge: Centaurus A

Low-energy cosmic rays are abundant and come from all directions, mostly from within our own Milky Way galaxy. Until now the only source of cosmic ray particles known with certainty has been the sun. Cosmic rays from other likely sources such as exploding stars take meandering paths through space so that when they reach Earth it is impossible to determine their origins.

"But when you look at the highest-energy cosmic rays from the most violent sources, they point back to their sources. The challenge now is to record enough of these cosmic bullets to understand the processes that hurl them into space," said Paul Mantsch, project manager of the Pierre Auger Observatory.

Cosmic rays with energy higher than about 60 EeV lose energy in collisions with the cosmic microwave background, (radiation left over from the Big Bang that fills all of space). But cosmic rays from nearby sources are less likely to lose energy in collisions on their relatively short trip to Earth. Auger scientists found that most of the 27 events with energy above 57 EeV came from locations in the sky that include the nearest AGNs, within a few hundred million light years of Earth.

Scientists think that most galaxies have black holes at their centres, with masses ranging from a million to a few billion times the mass of our sun. The black hole at the centre of our Milky Way galaxy weighs about 3 million solar masses, but it is not an AGN. Galaxies that have an AGN seem to be those that suffered a collision with another galaxy or some other massive disruption in the last few hundred million years. The AGN swallows the mass coming its way while releasing prodigious amounts of radiation. The Auger result indicates that AGNs may also produce the universe's highest-energy particles.

Cosmic-ray astronomy is challenging, because low-energy cosmic rays provide no reliable information on the location of their sources: as they travel across the cosmos, they are deflected by galactic and intergalactic magnetic fields that lead to blurry images. In contrast, the most energetic particles come almost straight from their sources, as they are barely affected by the magnetic fields. Unfortunately, they hit Earth at a rate of only about one event per square kilometre per century, which demands a very large observatory.

Because of its size, the Auger Observatory can record about 30 ultra-high-energy events per year. The Auger collaboration is developing plans for a second, larger installation in Colorado to extend coverage to the entire sky while substantially increasing the number of high-energy events recorded.

"Our current results show the promising future of cosmic-ray astronomy," said Auger co-spokesperson Giorgio Matthiae, of the University of Rome. "So far we have installed 1400 of the 1600 particle detectors of the Auger Observatory in Argentina. A northern site would let us look at more galaxies and black holes, increasing the sensitivity of our observatory. There are even more nearby AGNs in the northern sky than in the southern sky."

Source: Auger Observatory closes in on long standing mystery, links highest-energy cosmic rays with violent black holes

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Breakthrough in Cosmic Ray mystery from SciTech
AGN and Ultra High Energy Cosmic Rays from Space Daily
AUGER: millions of TeV cosmic rays from black holes from The Reference Frame
Ultra High Energy Cosmic Rays (UHECR) from Auger @ BackReaction
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Stellar Bubble Blower

2007-11-10T10:54:00.000Z

HH 46/47. NASA/JPL-Caltech/T. Velusamy (Jet Propulsion Laboratory)

A new image from NASA's Spitzer Space Telescope shows a baby star 1,140 light-years away from Earth blowing two massive "bubbles." This young Star, called HH 46/47, is using powerful jets of gas to make bubbles in outer space.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are from starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. Red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

According to Dr. Thangasamy Velusamy of NASA's Jet Propulsion Laboratory in Pasadena, Calif., baby stars and their potential planet-forming disks grow by gravitationally pulling in and absorbing surrounding gas and dust. Scientists suspect that these disks stop growing when the central baby star develops powerful winds and jets that blow away surrounding material.

"Spitzer can image these jets and winds in infrared light and help us understand the details of these phenomena," says Velusamy.

Spitzer's supersensitive infrared instruments are excellent tools for studying young stars embedded within thick clouds of cosmic dust and gas, revealing information about their growth.

When you see a star through a telescope, its image is blurred in a known way. The smaller the telescope the larger is the blurring.

To clear up this blurring, astronomers at JPL developed an advanced image-processing technique for Spitzer data called Hi-Res deconvolution. This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When Velusamy and his team applied this technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

According to Dr. William Langer, also of JPL, this image will help scientists determine which of many different mechanisms are responsible for producing the winds and jets of baby stars.

This infrared image is a three-colour composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.
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Light from Young Galaxies

2007-11-08T08:49:00.000Z

The artist's illustration shows a typical massive galaxy as it would have appeared when the universe was only about a quarter of its current age. This young galaxy contains an active galactic nucleus (AGN), or quasar, in its center, a luminous object powered by the rapid growth of a supermassive black hole. Some of the light from the AGN is obscured by dense gas and dust near the center of the galaxy. The galaxy itself is undergoing a growth spurt, as shown by bright regions of star formation in the spiral arms.

Spitzer Space Telescope observations are extremely efficient at detecting distant AGN like this because dust and gas should absorb high-energy radiation from the AGN and re-emit it at longer wavelengths, generating copious amounts of infrared emission.

Large numbers of galaxies thought to contain such highly obscured AGN have been discovered in the Great Observatories Origins Deep Survey. The infrared emission for these galaxies exceeds the levels likely to be caused by star formation. However, X-ray observations were required to confirm the presence of obscured AGN, by looking for the high energy X-rays expected from such objects (less energetic X-rays are mostly absorbed).
[+/-] Click here to expand

The image on the left shows a "stacked" Chandra image of distant, massive galaxies detected with Spitzer. Image stacking is a procedure used to detect emission from objects that is too faint to be detected in single images. To enhance the signal, images of these faint objects are stacked on top of one another. In this image, low-energy X-rays are shown in orange and high-energy X-rays in blue, and the stacked object is in the center of the image (the other sources beyond the center of the image are individual AGN that were directly detected and are not part of the source stacking).

The blue stacked source confirms the hypothesis that large numbers of these young, massive galaxies contain heavily obscured AGN. Spitzer also detected infrared emission from young, massive galaxies that is consistent with expectations for star formation. These galaxies do not contain AGN, because their supermassive black holes are dormant.

A stacked Chandra image (right) of these "normal" massive galaxies shows mainly soft X-ray emission at the center, as expected.

This image, taken with Spitzer's infrared vision, shows a fraction of these black holes, which are located deep in the bellies of distant, massive galaxies. Spitzer originally scanned the field of galaxies shown in the picture as part of a multiwavelength program called the Great Observatories Origins Deep Survey, or Goods.

This picture shows a portion of the Goods field called Goods-South. When astronomers saw the Spitzer data, they were surprised to find that hundreds of the galaxies between 9 and 11 billion light years away were shining with an unexpected excess of infrared light.

They then followed up with X-ray data from Chandra of the same field, and applied a technique called stacking, which adds up the faint light of multiple galaxies. The results revealed that the infrared-bright galaxies are hiding many black holes that had been theorized about before but never seen. This excess infrared light is being produced by the growing black holes.

Credit: Illustration: NASA/JPL-Caltech/T.Pyle (SSC); X-ray: NASA/CXC/Durham/D.Alexander et al.; Infrared: NASA/JPL-Caltech/CEA/E.Daddi

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Monster black holes power highest-energy cosmic rays from SNS
Cosmic 'Bullets' Traced to Galactic Black Holes from Live Science
'Violent' Black Holes Linked To High Energy Cosmic Rays from Scientic Blogging
Finding Antimatter & Collecting Natural Antimatter Centauri Dreams
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Powerful Cosmic Winds

2007-11-06T21:08:00.000Z

Black Holes Launch Powerful Cosmic Winds
Black holes often are thought of as just endless pits in space and time that destroy everything they pull toward them. But new findings confirm the reverse is true, too: Black holes can drive extraordinarily powerful winds that push out and force star formation and shape the fate of a galaxy.

Supermassive black holes are suspected to lurk in the hearts of many - if not all - large galaxies. These holes drag gas inward, which accrues in rapidly spinning, glowing disks.

Astronomers have long thought that such "accretion disks" give off mighty winds that shape the host galaxies, profoundly influencing how they grow.

"In the early universe, galaxies formed from clumps of gas coagulating from mutual gravitational attraction. If unhindered, they would have formed rather bigger structures than what we see today," said astrophysicist Andrew Robinson at the Rochester Institute of Technology in New York. "But if we take into account these winds blowing away surrounding gas, that could help explain the galaxy sizes we see."

Until now, scientists had only theorized that accretion disks launched these winds. No one had actually seen this happen. These accretion disks are comparable in size to our solar system - big for us - but on the scale of galaxies they're really tiny, and far away to boot, making it virtually impossible to distinguish any details such as winds.

To attempt to observe the winds, Robinson and his colleagues investigated a galaxy roughly 3 billion light years from Earth using the William Herschel Telescope on the Canary Islands off the coast of Africa. At the core of that galaxy lies a quasar, an extremely powerful source of radiation as bright as up to 1 trillion suns that originates from the superheated gas of a black hole's accretion disk.

The researchers discovered that light from the quasar was scattered by electrons in super-fast gas. The specific way in which this light was scattered suggests the gas was rotating at speeds similar to the accretion disk's rate of spin. In other words, they confirmed the accretion disk was launching wind.

The researchers will next try to find out if these disk winds are launched only when the black hole is growing rapidly, or just by quasars, which have the most massive black holes, or by all active galactic nuclei.

Findings detailed in the Nov. 1 issue of the journal Nature.
By Charles Q. Choi @ Live Science
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'Spitting' black holes may be key to cosmic mysteries from Space New Scientist
Supermassive Black Holes Produce Powerful Galaxy-shaping Winds - Science Daily
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Weighing the Universe's Mass

2007-11-05T18:30:00.000Z

Spiral Galaxy NGC1232 Credit: ESO.

This image of the large spiral galaxy NGC 1232 was obtained with the Very Large Telescope (VLT). Its distance from Earth is about 100 million light-years. It is thought to contain more dark matter than visible matter.

The same University of Alabama (UAH) group that in 2002 found what was theorized to be a significant fraction of the "missing mass" that binds together the universe has discovered that some x-rays thought to come from intergalactic clouds of "warm" gas are instead probably caused by lightweight electrons.

If the source of so much x-ray energy is tiny electrons instead of hefty atoms, it is as if billions of lights thought to come from billions of aircraft carriers were found instead to come from billions of extremely bright fireflies.

"This means the mass of these x-ray emitting clouds is much less than we initially thought it was," said Dr. Max Bonamente, an assistant professor in UAH's Physics Department. "A significant portion of what we thought was missing mass turns out to be these 'relativistic' electrons."

Travelling at almost the speed of light (and therefore "relativistic"), these feather weight electrons collide with photons from the cosmic microwave background. Energy from the collisions converts the photons from low-energy microwaves to high-energy x-rays.

In 2002 the UAH team reported finding large amounts of extra "soft" (relatively low-energy) x-rays coming from the vast space in the middle of galaxy clusters. This was in addition to previously-discovered "hot" gas in that space, which emits higher energy "hard" x-rays.

Although the soft x-ray-emitting atoms were thought to be spread thinly through space (less than one atom per cubit meter), they would have filled billions of billions of cubic light years. Their cumulative mass was though to account for as much as ten percent of the mass and gravity needed to hold together galaxies, galaxy clusters and perhaps the universe itself.

When Bonamente and his associates looked at data gathered by several satellite instruments, including the Chandra X-ray Observatory, from a galaxy cluster in the southern sky, however, they found that energy from those additional soft x-rays doesn't look like it should.

"We have never been able to detect spectral emission lines associated with those detections," he explained. "If this 'bump' in the data were due to cooler gas, it would have emission lines."

The best, most logical explanation seems to be that a large fraction of the energy comes from electrons smashing into photons instead of from warm atoms and ions, which would have recognizable spectral emission lines. Finding these electrons, however, is like finding "the tip of the iceberg," said Bonamente, because they would not be limited to emitting only the soft x-ray signal. The signal from these electrons would also make up part of the previously observed harder X-rays, which would reduce the amount of mass thought to make up the hot gas at the center of galaxy clusters.

The energy from these electrons might also "puff up" the cluster. Previously, astrophysicists used the energy coming from inside these clusters to calculate how much mass is needed to reach the equilibrium seen there; too much mass and the cloud would collapse; too little and the hot gas cloud would expand. Since the energy coming from these hot clouds can be accurately measured, it was thought the mass could be calculated with reasonable confidence.

Instead, says Bonamente, if a significant portion of the total x-ray energy comes from fast electrons, "that could trick us into thinking there is more gas than is actually there." It means we need to revise how we calculate both the gas mass and the total mass. If part of the hard x-ray energy comes from electrons and photons, it might also shift what we think is the mix of elements in the universe.

Outside of the excess soft x-rays, the x-ray energy coming from galaxy clusters has emission lines which are especially prominent around iron and other metals. Non-thermal x-rays from electrons colliding with photons might mask those emission lines, like thick snow can mask the height of fence posts. "This is also telling us there is fractionally more iron and other metals than we previously thought," said Bonamente. "Less mass but more metals."
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Missing Mass Theory Revised from Centauri Dreams
Big Chunk Of The Universe Is Missing - Again from Science Daily
Dark Matter & visible Matter in Galaxies from Life in the Universe
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Dark 'Black Eye' Galaxy

2007-11-03T11:51:00.000Z

Messier 64 (M64) has a spectacular dark band of absorbing dust in front of the galaxy's bright nucleus, giving rise to its nicknames of the "Black Eye" galaxy.

Fine details of the dark band are revealed in this image of the central portion of M64 obtained with the Hubble Space Telescope. First cataloged in the 18th century by the French astronomer Messier, M64 is located in the northern constellation Coma Berenices, and resides roughly 17 million light-years from Earth.

At first glance, M64 appears to be a fairly normal pinwheel-shaped spiral galaxy. As in the majority of galaxies, all of the stars in M64 are rotating in the same direction, clockwise as seen in the Hubble image. However, detailed studies in the 1990's led to the remarkable discovery that the interstellar gas in the outer regions of M64 rotates in the opposite direction from the gas and stars in the inner regions.

Active formation of new stars is occurring in the shear region where the oppositely rotating gases collide, are compressed, and contract. Particularly noticeable in the image are hot, blue young stars that have just formed, along with pink clouds of glowing hydrogen gas that fluoresce when exposed to ultraviolet light from newly formed stars.

Astronomers believe that the oppositely rotating gas arose when M64 absorbed a satellite galaxy that collided with it, perhaps more than one billion years ago. This small galaxy has now been almost completely destroyed, but signs of the collision persist in the backward motion of gas at the outer edge of M64.

This image of M64 was taken with Hubble's Wide Field Planetary Camera 2 (WFPC2). The colour image is a composite from pictures taken through four different colour filters. These filters isolate blue and near-infrared light, along with red light emitted by hydrogen atoms and green light from Strömgren y.
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Modified Gravity in the absence of Dark Matter
Dark Matter's Rival Theory Challenges "Invisible Mass"
Supermassive Black Holes Shape Their Galaxies from Universe Today
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Massive "Stellar" Black Hole

2007-11-01T08:58:00.000Z

Credit: Aurore Simonnet/Sonoma State University/NASA

Astronomers have discovered a massive stellar black hole with an orbiting companion: a hot, highly evolved star. The new black hole, is the heftiest known black hole that orbits another star.

Formed in the death throes of massive stars, "stellar-mass" black holes are smaller than the monster black holes found in galactic cores. The previous record holder for largest stellar-mass black hole is a 16-solar-mass black hole in the galaxy M33, announced on October 17.

Located in the nearby dwarf galaxy IC 10, 1.8 million light-years from Earth in the constellation Cassiopeia. The star is ejecting gas in the form of a wind. Some of this material spirals toward the black hole, heats up, and gives off powerful X-rays before crossing the point of no return.

In November 2006, Andrea Prestwich of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and her colleagues observed the dwarf galaxy with NASA’s Chandra X-ray Observatory.

The group discovered that the galaxy’s brightest X-ray source, IC 10 X-1, exhibits sharp changes in X-ray brightness. Such behavior suggests a star periodically passing in front of a companion black hole and blocking the X-rays, creating an eclipse. In late November, NASA’s Swift satellite confirmed the eclipses and revealed details about the star’s orbit.

The star in IC 10 X-1 appears to orbit in a plane that lies nearly edge-on to Earth’s line of sight, so a simple application of Kepler’s Laws show that the companion black hole has a mass of at least 24 Suns.

The black hole’s large mass is surprising because massive stars generate powerful winds that blow off many Suns worth of gas before the stars explode. Calculations suggest massive stars in our galaxy leave behind black holes no heavier than about 15 Suns.

The IC 10 X-1 black hole has gained mass since its birth by gobbling up gas from its companion star, but the rate is so slow that the black hole would have gained no more than 1 or 2 solar masses. "This black hole was born fat; it didn’t grow fat," says astrophysicist Richard Mushotzky of NASA Goddard Space Flight Center in Greenbelt, Md., who is not a member of the discovery team.

The progenitor star probably started its life with 60 or more solar masses. Like its host galaxy, it was probably deficient in elements heavier than hydrogen and helium. In massive, luminous stars with a high fraction of heavy elements, the extra electrons of elements such as carbon and oxygen “feel” the outward pressure of light and are more susceptible to being swept away in stellar winds.

But with its low fraction of heavy elements, the IC 10 X-1 progenitor shed comparatively little mass before it exploded, so it could leave behind a heavier black hole.

"Massive stars in our galaxy today are probably not producing very heavy stellar-mass black holes like this one," says coauthor Roy Kilgard of Wesleyan University in Middletown, Conn. "But there could be millions of heavy stellar-mass black holes lurking out there that were produced early in the Milky Way’s history, before it had a chance to build up heavy elements."

This release is being issued jointly with NASA
Massive Black Hole Smashes Record
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New Spin on how Stars Are Born from Live Science
Black Holes may harbour their own universes from Space New Scientist
White Dwarf "Sibbling Rivalry" explodes into Supernova CfA Press Release
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The Ghost Head Nebula

2007-10-31T10:48:00.000Z

NGC 2080. Credit: Mohammad Heydari-Malayeri (Observatoire de Paris) et al

This image from NASA's Hubble Space Telescope reveals a vibrant green and red nebula far from Earth, where nature seems to have put on the traditional colours of the season. These colours, produced by the light emitted by oxygen and hydrogen, help astronomers investigate the star-forming processes in nebulas such as NGC 2080.

The light from the nebula captured in this image is emitted by two elements, hydrogen and oxygen. The red and the blue light are from regions of hydrogen gas heated by nearby stars. The green light on the left comes from glowing oxygen. The energy to illuminate the green light is supplied by a powerful stellar wind (a stream of high-speed particles) coming from a massive star just outside the image.

The white region in the center is a combination of all three emissions and indicates a core of hot, massive stars in this star-formation region. The intense emission from these stars has carved a bowl-shaped cavity in the surrounding gas.

In the white region, the two bright areas (the "eyes of the ghost") - named A1 (left) and A2 (right) - are very hot, glowing "blobs" of hydrogen and oxygen. The bubble in A1 is produced by the hot, intense radiation and powerful stellar wind from a single massive star. A2 has a more complex appearance due to the presence of more dust, and it contains several hidden, massive stars. The massive stars in A1 and A2 must have formed within the last 10,000 years, since their natal gas shrouds are not yet disrupted by the powerful radiation of the newly born stars.

This "enhanced colour" picture spanning 55 light years in the above image is composed of three narrow-band-filter images obtained with Hubble's Wide Field Planetary Camera 2. The colours are red (ionized hydrogen, H-alpha, 1040 seconds), green (ionized oxygen, 1200 seconds) and blue (ionized hydrogen, H-beta, 1040 seconds).

The Ghost Head Nebula NGC 2080 is a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way.

Halloween's ancient & astronomical origins date back to the ancient Celtic festival of Samhain (pronounced sow-in).
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The Celts, who lived 2,000 years ago in the area that is now Ireland, the United Kingdom, and northern France, celebrated their new year on November 1. This day marked the end of summer and the harvest and the beginning of the dark, cold winter, a time of year that was often associated with human death. Celts believed that on the night before the new year, the boundary between the worlds of the living and the dead became blurred. On the night of October 31, they celebrated Samhain, when it was believed that the ghosts of the dead returned to earth. In addition to causing trouble and damaging crops, Celts thought that the presence of the otherworldly spirits made it easier for the Druids, or Celtic priests, to make predictions about the future. For a people entirely dependent on the volatile natural world, these prophecies were an important source of comfort and direction during the long, dark winter.

To commemorate the event, Druids built huge sacred bonfires, where the people gathered to burn crops and animals as sacrifices to the Celtic deities.

During the celebration, the Celts wore costumes, typically consisting of animal heads and skins, and attempted to tell each other's fortunes. When the celebration was over, they re-lit their hearth fires, which they had extinguished earlier that evening, from the sacred bonfire to help protect them during the coming winter.

By A.D. 43, Romans had conquered the majority of Celtic territory. In the course of the four hundred years that they ruled the Celtic lands, two festivals of Roman origin were combined with the traditional Celtic celebration of Samhain.

The first was Feralia, a day in late October when the Romans traditionally commemorated the passing of the dead. The second was a day to honor Pomona, the Roman goddess of fruit and trees. The symbol of Pomona is the apple and the incorporation of this celebration into Samhain probably explains the tradition of "bobbing" for apples that is practiced today on Halloween.

By the 800s, the influence of Christianity had spread into Celtic lands. In the seventh century, Pope Boniface IV designated November 1 All Saints' Day, a time to honor saints and martyrs. It is widely believed today that the pope was attempting to replace the Celtic festival of the dead with a related, but church-sanctioned holiday. The celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints' Day) and the night before it, the night of Samhain, began to be called All-hallows Eve and, eventually, Halloween. Even later, in A.D. 1000, the church would make November 2 All Souls' Day, a day to honor the dead. It was celebrated similarly to Samhain, with big bonfires, parades, and dressing up in costumes as saints, angels, and devils. Together, the three celebrations, the eve of All Saints', All Saints', and All Souls', were called Hallowmas.

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Seeing Colour in Nebulae from A Quantum Diaries Survivor
Celestial Mandrill Is A Cosmic Ghost from Scientific Blogging
Astronomers simulate life & death in the Universe from Science Daily
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Dancing With The Stars

2007-10-30T16:50:00.000Z

Arp 87. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Two galaxies perform an intricate dance in this new Hubble Space Telescope image. The galaxies, containing a vast number of stars, swing past each other in a graceful performance choreographed by gravity.

The pair, known collectively as Arp 87, is one of hundreds of interacting and merging galaxies known in our nearby universe.
Arp 87 was originally cataloged by astronomer Halton Arp in the mid 1960s. Arp's Atlas of Peculiar Galaxies is a compilation of astronomical photographs using the Palomar 200-inch Hale and the 48-inch Samuel Oschin telescopes.

The resolution in the Hubble image shows exquisite detail and fine structure that was not observable when Arp 87 was first cataloged in the 1960s.

The two main players comprising Arp 87 are NGC 3808 on the right (the larger of the two galaxies) and its companion NGC 3808A on the left. NGC 3808 is a nearly face-on spiral galaxy with a bright ring of star formation and several prominent dust arms. Stars, gas, and dust flow from NGC 3808, forming an enveloping arm around its companion. NGC 3808A is a spiral galaxy seen edge-on and is surrounded by a rotating ring that contains stars and interstellar gas clouds. The ring is situated perpendicular to the plane of the host galaxy disk and is called a "polar ring."

As seen in other mergers similar to Arp 87, the corkscrew shape of the tidal material or bridge of shared matter between the two galaxies suggests that some stars and gas drawn from the larger galaxy have been caught in the gravitational pull of the smaller one. The shapes of both galaxies have been distorted by their gravitational interaction with one another.

Interacting galaxies often exhibit high rates of star formation. Many lines of evidence - colours of their starlight, intensity of emission lines from interstellar gas, far-infrared output from heated interstellar dust - support this fact. Some merging galaxies have the highest levels of star formation we can find anywhere in the nearby universe.

A major aspect of this excess star formation could be properly revealed only when Hubble turned its imaging capabilities toward colliding galaxies. Among the observatory's first discoveries was that galaxies with very active star formation contain large numbers of super star clusters - clusters more compact and richer in young stars than astronomers were accustomed to seeing in our galactic neighbourhood.

Arp 87 is in the constellation Leo, the Lion, approximately 300 million light-years away from Earth. These observations were taken in February 2007 with the Wide Field Planetary Camera 2. Light from four isolated wavelength ranges (centred around 450, 555, 656 and 814 nm) blue, green, red, and infrared ranges was composited together to form this colour image.
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Essence of Living

2007-10-28T07:04:00.000Z

Horse - courtesy of Katie @ Katie's Poetry Corner

Doesn't take a horse long to learn
that into four legs a horse is born

Doesn't take a horse long to learn
that head and tail a horse can turn

Doesn't take a horse long to learn
a horse full of energy to run & burn

Doesn't take a horse long to learn
that to run & gallop a horse is born

But can the horse remember who or what the horse has been
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Side by Side from Anna-lys @ Anna-lys blogspot
Being Present - from Pandabonium @ Pacific Islander
Other universes may be detectable from World of Science
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Distant Ancient Black Holes

2007-10-26T08:30:00.000+01:00

Hundreds of "missing" black holes have been found lurking in dusty galaxies located 9 billion to 11 billion light-years away and existed at a time when the universe was between 2.5 and 4.5 billion years old.

"Active, supermassive black holes were everywhere in the early universe," said study team member Mark Dickinson of the National Optical Astronomy Observatory in Tuscon, Ariz. "We had seen the tip of the iceberg before in our search for these objects. Now, we can see the iceberg itself."

The finding, detailed in two studies published in the Nov. 10 issue of Astrophysical Journal, is the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths constructing supermassive black holes at their cores.

It could also help answer fundamental questions about how massive galaxies such as our Milky Way evolved.

Using NASA's Chandra X-ray and Spitzer Space Telescopes, the team detected unusually high levels of infrared light emitted by 200 galaxies in the distant universe. They think the infrared light was created by material falling into "quasars"-supermassive black holes surrounded by doughnut-shaped clouds of gas and dust-at the center of the galaxies.

The new quasar-containing galaxies are all about the same mass as our Milky Way, but are irregular in shape. For decades, scientists have predicted that a large population of quasars should be found at those distances but had only spotted a few of them.

The newfound quasars confirm what scientists have suspected for years now: that supermassive black holes play a major role in star formation in massive galaxies. The observations suggest massive galaxies steadily build up their stars and black holes simultaneously until they get too big and the black holes suppress star formation.

The new quasars also suggest that collisions between galaxies might not be as important for galaxy evolution as once thought. "Theorists thought mergers between galaxies were required to initiate this quasar activity, but now we see that quasars can be active in unharassed galaxies," said study team member David Alexander of Durham University in the UK.
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The improbable Universe by Pamela Star Stryder
Hubble Spies Shells of Sparkling Stars around Quasars
Texture discovered in Fabric of Space-Time from Scientific Blogging
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A Glowing Pool of Light

2007-10-25T12:58:00.000+01:00

Planetary Nebula NGC 3132 - Click on Image to Enlarge

NGC 3132 is a striking example of a planetary nebula. This expanding cloud of gas, surrounding a dying star, is known in the southern hemisphere as the "Eight-Burst" or the "Southern Ring" Nebula.

The name "planetary nebula" refers only to the round shape that many of these objects show when examined through a small visual telescope. In reality, these nebulae have little or nothing to do with planets, but are instead huge shells of gas ejected by stars as they near the ends of their lifetimes.

NGC 3132 is nearly half a light year in diameter, and at a distance of about 2000 light years is one of the nearer known planetary nebulae. The gases are expanding away from the central star at a speed of 9 miles per second.

This image, captured by NASA's Hubble Space Telescope, clearly shows two stars near the center of the nebula, a bright white one, and an adjacent, fainter companion to its upper right. (A third, unrelated star lies near the edge of the nebula.) The faint partner is actually the star that has ejected the nebula. This star is now smaller than our own Sun, but extremely hot. The flood of ultraviolet radiation from its surface makes the surrounding gases glow through fluorescence. The brighter star is in an earlier stage of stellar evolution, but in the future it will probably eject its own planetary nebula.

In the Heritage Team's rendition of the Hubble image, the colours were chosen to represent the temperature of the gases. Blue represents the hottest gas, which is confined to the inner region of the nebula. Red represents the coolest gas, at the outer edge. The Hubble image also reveals a host of filaments, including one long one that resembles a waistband, made out of dust particles which have condensed out of the expanding gases. The dust particles are rich in elements such as carbon. Eons from now, these particles may be incorporated into new stars and planets when they form from interstellar gas and dust. Our own Sun may eject a similar planetary nebula some 6 billion years from now.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: R. Sahai (Jet Propulsion Lab)
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G292.0+1.8

2007-10-23T22:32:00.000+01:00

Credit: X-ray: NASA/CXC/Penn State/S.Park et al.; Optical: Pal.Obs. DSS

When a massive star explodes, it creates a shell of hot gas that glows brightly in X-rays. Chandra is able to observe the stellar debris, revealing the dynamics of the explosion.

Located about 20,000 light years away in the constellation of Centaurus, G292.0+1.8 is shown in beautiful detail in this new composite image. In colour is the Chandra X-ray Observatory image - easily the deepest X-ray image ever obtained of this supernova remnant - and in white is optical data from the Digitized Sky Survey.

Although considered a "textbook" case of a supernova remnant, the intricate structure shown here reveals a few surprises.

Near the center of G292.0+1.8 is the so-called pulsar wind nebula, most easily seen in high energy X-rays. This is the magnetized bubble of high-energy particles that surrounds the "pulsar", a rapidly rotating neutron star that remained behind after the original, massive star exploded. The narrow, jet-like feature running from north to south in the image is likely parallel to the spin axis of the pulsar.
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The pulsar is located slightly below and to the left of the center of G292.0+1.8. Assuming that the pulsar was born at the center of the remnant, it is thought that recoil from the lopsided explosion may have kicked the pulsar in this direction. However, the kick direction and the pulsar spin direction do not appear to be aligned, in contrast to apparent spin-kick alignments seen in some other supernova remnants.

Another key feature of this remnant is the long white line running from left to right across the center called the equatorial belt. This structure is thought to be created when the star - before it died - expelled material from around its equator via winds. The orientation of the equatorial belt suggests the parent star maintained the same spin axis both before and after it exploded.

One puzzling aspect of the image is the lack of evidence for thin filaments of high energy X-ray emission, thought to be an important site for cosmic ray acceleration in supernova remnants. These filaments are seen in other supernova remnants such as Cassiopeia A, Tycho and Kepler.

One explanation may be that efficient acceleration occurs primarily in very early stages of supernova remnant evolution, and G292.0+1.8, with an estimated age of several thousand years, is too old to show these effects. Casseiopeia A, Tycho and Kepler, with ages of several hundred years, are much younger.

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The Unseen & The Unknown

2007-10-22T21:55:00.000+01:00

The enigmatic neutrinos are among the most abundant of the tiny particles that make up our universe. They are a billion times more abundant than the particles of which the earth and we humans are made.

Thus, to understand the universe, we must understand the neutrinos. Moving ghostlike, almost invisibly, through matter, these particles are very hard to pin down and study. However, dramatic progress has recently been made. Fermilab's Boris Kayser SLAC 2005 lecture.

Neutrinos are elementary particles that travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed, and are thus extremely difficult to detect. Neutrinos have a minuscule, but non-zero, mass too small to be measured as of 2007. Usually denoted by the Greek letter ν (nu).

Neutrinos are created as a result of certain types of radioactive decay or nuclear reactions such as those in the sun, in nuclear reactors, or when cosmic rays hit atoms. There are three types, or “flavours”, of neutrinos: electron neutrinos, muon neutrinos and tau neutrinos; each type also has an antimatter partner, called an antineutrino. Electron neutrinos are generated whenever protons change into neutrons, while electron antineutrinos are generated whenever neutrons change into protons. These are the two forms of beta decay. Interactions involving neutrinos are generally mediated by the weak nuclear force.

Most neutrinos passing through the Earth emanate from the sun, and more than 50 trillion solar electron neutrinos pass through the human body every second.

But even if and when we can detect every elementary particle, component or 'strings' in the universe, will we be able to categorically state that nothing survives death, or that heaven is not sitting safely cocooned on some far off distant galaxy of the observable universe.

Perhaps this universe is not the best of all possible universes, but simply the universe we ‘observe’ while we are in it - and there are other universes, in One of which, neither time ageing or decay exist or are of any consequence.

After all, have we given a name to that which is beyond the cosmic event horizon or beyond the ‘observable’ universe, and what proof do we have that what is beyond is an empty ‘nothingness’ or vacuum. Even a Torus is surrounded by ’something’ on all sides.

Since with current technology, science & knowledge we are unable to travel the length of our solar system in a lifetime, should we therefore conclude that interstellar & intergalactic travel is ‘beyond’ the human race’s capability. Or should we be prepared to admit that there is much we do not know, and there are advances we hope to make. But even when we think we know everything, or at least everything about the observable universe (including visible matter and dark matter) will we ever be any closer to the great Unknown.
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Magnetic Cocoons power energetic Cosmic Rays @ NewScientistSpace
Genesis - Clues to the Origins of the Solar System @ The Daily Galaxy
Enormous Bubbles of Plasma - trapped - within Earth's Magnetic Field
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Scorpius - Sky Spectacular

2007-10-20T00:37:00.000+01:00

Credit & Copyright: Stéphane Guisard. - Click Image to Enlarge

Scorpius more typically appears as a few bright stars in a well known but rarely pointed out zodiacal constellation.

To get a spectacular image like this, though, one needs a good camera, colour filters, and a digital image processor. To bring out detail, the above image not only involved long duration exposures taken in several colours, but one exposure in a very specific red colour emitted by hydrogen that brings out great detail.

The resulting image shows many breathtaking features. Vertically across the image left is part of the plane of our Milky Way Galaxy. Visible there are vast clouds of bright stars and long filaments of dark dust. Jutting out diagonally from the Milky Way in the image center are dark dust bands known as the Dark River.

This river connects to several bright stars on the right that are part of Scorpius' head and claws, and include the bright star Antares.

Above and right of Antares is an even brighter planet Jupiter. Numerous red emission nebulas and blue reflection nebulas are visible throughout the image. Scorpius appears prominently in southern skies after sunset during the middle of the year.
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ESA's Candidate Missions

2007-10-19T11:03:00.001+01:00

Credits: Khosroshahi, Maughan, Ponman, Jones, ESA, ING.

XMM-Newton observations of the fossil galaxy cluster RX J1416.5+2315, show a cloud of hot gas emitting X-rays (in blue). The cloud, reaching temperatures of about 50 million degrees, extend over 3.5 million light years and surround a giant elliptical galaxy believed to have grown to its present size by cannibalising its neighbours.

XEUS, X-ray Evolving Universe Spectroscopy
XEUS is a next-generation X-ray space observatory to study the fundamental laws of the Universe and the origins of the universe. With unprecedented sensitivity to the hot, million-degree universe, XEUS would explore key areas of contemporary astrophysics: growth of supermassive black holes, cosmic feedback and galaxy evolution, evolution of large-scale structures, extreme gravity and matter under extreme conditions, the dynamical evolution of cosmic plasmas and cosmic chemistry. XEUS would be stationed in a halo orbit at L2, the second Lagrange point, with two satellites (one mirror satellite and the other a detector satellite) that would fly in formation.

ESA announces candidate missions for 2015-2025 Cosmic Vision
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Including space walking, spacecraft docking and the setting up of a space laboratory before 2010, China is also planning to land a human on the moon and to make a series of robotic missions with a view to building a base there after 2020.
China reveals space plans from Space Daily
NASA terminates Kistler Rocketplane contract from Cosmic Log
ESA's Integral Project ends its five year journey from Goldenship9
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Extreme Stellar Black Hole

2007-10-17T22:30:00.000+01:00

Credit: NASA/CXC/M. Weiss

An artist's representation of M33 X-7: a binary system in the nearby galaxy M33, containing a massive blue star feeding material to a black hole surrounded by a small accretion disk.

Stellar black holes form when stars with masses around 20 times that of the sun collapse under the weight of their own gravity at the ends of their lives. Most stellar black holes weigh in at around 10 solar masses when the smoke blows away.

The black hole in M33 X-7 located 2.7 million light-years from Earth, is also the most distant stellar black hole ever observed.

The findings, detailed in the Oct. 17 issue of the journal Nature, could help improve formation models of "binary" systems containing a black hole and a star. It could also help explain one of the brightest star explosions ever observed.

The blackhole orbits a companion star in the spiral galaxy Messier 33. The companion star of M33 X-7 passes directly in front of the black hole as seen from Earth once every three days, completely eclipsing its X-ray emissions. It is the only known binary system in which this occurs, and it was this unusual arrangement that allowed astronomers to calculate the pair's masses very precisely.

The tight orbits of the black hole and star suggests the system underwent a violent stage of star evolution called the common-envelope phase, in which a dying star swells so much it sucks the companion inside its gas envelope.

The result is either a merger between the two stars or the formation of a tight binary in which one star is stripped of its outer layers. The latter scenario may be what happens in the case of M33 X-7, and the stripped star explodes as a supernova before imploding to form a black hole.

However, something unusual must have happened to M33 X-7 during this phase to create such a massive black hole. The black hole must have lost a large amount of mass for the two objects to be so close, but on the other hand, it must have retained enough mass to form such a heavy black hole.

M33 X-7 might thus provide both the upper and lower limits on the amount of mass loss and orbital tightening that can occur in the common envelope.

While the estimated 16 solar masses of the black hole in M33 X-7 is hefty for a stellar black hole, it is miniscule compared with the black holes thought to lie in the heart of many large galaxies.

Such "supermassive" black holes have masses millions to billions times that of our sun, but they are thought to form by mechanisms different from the stellar variety.

M33 X-7: Heaviest Stellar Black Hole Discovered in Nearby Galaxy from Chandra
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The fantastic skies of Orphan Stars from NASA Science
Hubble finds Youthful-looking galaxy conceals ancient stars
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The Universe Is All History

2007-10-16T21:59:00.000+01:00

It took 300 years of experiment and calculation to pin down the speed at which light travels in a vacuum: 186,282 miles per second.

Light will travel slightly slower than this through air, and some wild experiments have actually slowed light to a crawl and seemingly made it go backward, but at the scales encountered in our everyday lives, light is so fast that we perceive our surroundings in real time.

Look up into the night sky and this illusion begins to falter. Because light takes time to get here from there, the farther away 'there' is the further in the past light left there and so we see all objects at some time in the past.

We see the relatively close moon as it was 1.2 seconds ago and the more distant sun as it was about 8 minutes ago. The measurements — 1.2 light-seconds and 8 light-minutes — can be thought to describe both time and distance.

The distance to more remote objects such as other stars is so great it is measured in light-years—the distance light will travel in a year, or about 6 trillion miles (10 trillion kilometers). Even the nearest star system, Proxima Centauri, lies more than four light-years away, so it appears to us on Earth as it was just over four years ago when the light began its journey.
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In this way, light's finite speed gives us a valuable view into the past, and as we strain our gaze deeper into the universe we look further back in time. In the case of distant galaxies, we see them as they were billions of years ago when the universe was relatively young.

Glittering star cluster is galactic heavyweight This cluster of thousands of stars lies 20,000 light years from Earth in the Carina spiral arm of our galaxy. It is embedded in a star-forming nebula called NGC 3603, a cloud of gas and dust with enough material to form 400,000 stars like the Sun. Most of the bright stars in the image are very hot and massive. Their radiation and stellar winds have blown out a large cavity in the nebula around them.

Some galaxies are so remote that their light hasn't had sufficient time to reach us yet, despite about 13.7 billion years of travel.

There could also be more distant objects that will forever remain unknown to us. Because the universe may be expanding and the expansion appears to be accelerating, there may be distant galaxies which if we can't see them now because their light has not had time to reach us, we will never see.

So we can never see the universe as it is, only as it was at various stages of its development. To interact with remote parts of the universe — to see them as they are now — would require some exotic means of travel, such as to travel faster than light which, according to Einstein's special theory of relativity, is impossible as it would require an infinite amount of energy.

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The fantastic skies of Orphan Stars from NASA Science
Hubble finds Youthful-looking galaxy conceals ancient stars
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Future Space Craft

2007-10-15T23:03:00.000+01:00

The risks from radiation in space, and the need to keep the crew safe on long flights, may influence the shape of future spaceships.

The major radiation sources are galactic cosmic rays, charged particles: from electrons up to the heavy metal elements and 'solar particle events', which throw out protons and helium nuclei.

Exposure from the hazards of severe space radiation in long-duration deep space missions is 'the show stopper'. Protection from the hazards of severe space radiation is of paramount importance to NASA's new vision to reach the Moon, Mars and beyond.

The electrons, protons & heavy-metal ions such as iron and uranium whiz through the void and can all cause cancers. But aluminium shielding capable of staving the radiation off on extended journeys would be prohibitively heavy, burning too much fuel.

The ideal form, according to Ram Tripathi, a spaceflight engineer at NASA, is a grapefruit spiked with cherries on sticks. With positively and negatively charged metal spheres be arranged on struts jutting out of the crew capsule, in carefully controlled directions, to give the crew a high degree of electrostatic radiation cover.

Tripathi calculates the "cherries" would need to be between 10 and 20 metres in diameter and would be stationed about 50 metres from the crew capsule – the "grapefruit". These spheres would protect the crew by deflecting charged particles away from the central habitat. Spheres give you more volume and less mass, and evenly distribute the deflecting charges over their surface.

The charged spheres would be made of lightweight hollow aluminium, the material shielding the crew capsule would incorporate carbon nanotubes – in a novel composite with aluminium. The nanotubes are light, they can take a pounding from heavy incoming ions.

Or we could have spaceships with a more conventional shape like a submarine, the starship enterprise, the space shuttle or nerva, with a false skin filled with smaller spheres (or even tubes) having the same desired effect, deflecting radiation and adding volume, without overwhelmingly increasing the mass.

Laser power stations, drawing energy from the local environment, might one day propel spacecraft throughout the solar system. NASA studies of advanced planetary missions have ranged from small robotic probes to multiple-spacecraft human exploration missions.
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The completed International Space Station will have a mass of about 1,040,000 pounds. It will measure 356 feet across and 290 feet in length, with almost an acre of solar panels to provide electrical power to six laboratories.

The assembled space station will provide the first laboratory complex where gravity, a fundamental force on Earth, can be controlled for extended periods. This control of gravity opens up an unimaginable world where almost everything grows differently than on Earth. For example, purer protein crystals can be grown in space than on Earth. By analyzing crystals grown on the ISS, scientists may be able to develop medicines that target particular disease-causing proteins.

Such crystals for research into cancer, diabetes, emphysema and immune disorders grown on the space station have already shown promise. New drugs to fight influenza and post-surgery inflammation are already in clinical trials, and future research will benefit from the extended exposure to weightlessness available on the station.

Many of the changes in the human body that result from space flight mimic those seen on Earth as a result of aging. Understanding of the causes of these changes may lead to the development of countermeasures against bone loss, muscle atrophy, balance disorders and other symptoms common in an aging population.

The Johnson Space Centre, together with scientists and researchers at NASA's other field centers, is working on the technologies that will be required for further exploration of the universe in the next years. For example, a new rocket team at Marshall is developing revolutionary technologies that will make space transportation as safe, reliable and affordable as today's airline transportation.

Hospitals, business parks and solar electric power stations that beam clean, inexpensive energy back to Earth are likely to dot the "space-scape" 40 years from now. Space adventure tourism and travel, orbiting movie studios, and worldwide, two-hour express package delivery also appear just over the horizon.

By 2040, it's expected to cost only tens of dollars per pound to launch humans or cargo to space; today, it costs as much as $10,000 per pound. Bridging that gap requires intense research and technology development focused on accelerating breakthroughs that will serve as keys to open the space frontier for business and pleasure.

Space transportation technology breakthroughs will launch a new age of space exploration, just as the silicon chip revolutionized the computer industry and made desktop computers commonplace.

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The New Space Race by Brian Appleyard @ The Sunday Times
The first Sino-European Satellite completes four year mission ESA
The Johnson Space Centre Celebrates 40 Years of Human Space Flight
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Solar Power from Space

2007-10-13T09:17:00.000+01:00

Illustration: Mafic Studios

A report released by the National Security Space Office recommends that the US government sponsor projects to demonstrate solar-power-generating satellites and provide financial incentives for further private development of the technology.

Space-based solar power would use kilometre-sized solar panel arrays to gather sunlight in orbit. It would then beam power down to Earth in the form of microwaves or a laser, which would be collected in antennas on the ground and then converted to electricity. Unlike solar panels based on the ground, satellites placed in geostationary orbit above the Earth can operate at night and during cloudy conditions.

The NSSO report (pdf) recommends that the US government spend $10 billion over the next 10 years to build a test satellite capable of beaming 10 megawatts of electric power down to Earth.
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At the same press conference, over a dozen space advocacy groups announced a new alliance to promote space solar power – the Space Solar Alliance for Future Energy. These supporters of space-based solar power say the technology has the potential to provide more energy than fossil fuels, wind and nuclear power combined.

The NSSO report says that solar-power-generating satellites could also solve supply problems in distant places such as Iraq, where fuel is currently trucked along in dangerous convoys and the cost of electricity for some bases can exceed $1 per kilowatt-hour. The report also touts the technology's potential to provide a clean, abundant energy source and reduce global competition for oil.

The US abandoned the idea as economically unfeasible in the 1970s. Advances in photovoltaics, electronics and robotics will bring the size and cost down to a fraction of the original schemes, and eliminate the need for humans to assemble the equipment in space.

Several technical challenges remain to be overcome, including the development of lower-cost space launches. A satellite capable of supplying the same amount of electric power as a modern fossil-fuel plant would have a mass of about 3000 tonnes – more than 10 times that of the International Space Station. Sending that material into orbit would require more than a hundred rocket launches. The US currently launches fewer than 15 rockets each year.

In spite of these challenges, the NSSO say no fundamental scientific breakthroughs are necessary to proceed with the idea and that space-based solar power will be practical in the next few decades.

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Beaming Power from Space by Astroprof @ Astroprof's Page
Harnessing The Sun interview with Feng Hsu @ Scientic Blogging
Internet 2 Speeds Jump 10-fold -To Debut at CERN - The Daily Galaxy
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The Dandelion Universe

2007-10-12T09:49:00.001+01:00

So we don't all live on a yellow submarine.
We live in a universe which rapidly inflated from a 'nothingness' and expanded into the universe we observe today, a place filled with the visible matter and a lot of dark matter (and dark energy) contained within the cosmic event horizon.

And though for a while we may have thought the expansion of the universe was contained by gravity and/or a sort of surface tension of the outer rim (skin) or cosmic event horizon, it now seems that the universe may still be expanding and even accelerating - perhaps taking the shape of the spiral galaxies we observe, including our own home the Milky Way

And yes it is possible that anything on the outer limits may accelerate and reach the speed of light, or even fall outside (escape) the cosmic event horizon. Of course this may already have happened to some of the original universe. We would be unable to tell, since we cannot see beyond the event horizon.

These things occur on a cosmological time-scale, so it is not easy for us to see in a human life-time. In the mean time we amuse ourselves trying to speculate, theorize and debate what may have occurred billions of years ago, and what may be the consequences now & today billions of light years away.
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Testing Einstein: Is Dark Energy Constant? - CfA Press Release
Major Step Toward Knowing Origin of Cosmic Rays - from NASA
Stellar Explosion Outshines Sun 100 Billion Times @ Live Science
Orion Measurements Change Stellar Distances - Centauri Dreams
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