Thursday, August 30, 2007

Planet Forming Supersonic Rain

Swirling disc of gas & dust surrounds a developing star (Illustration: NASA/JPL-Caltech)

Water from space is 'raining' onto a planet-forming disc at supersonic speeds, new observations from the Spitzer Space Telescope reveal. The unprecedented detail of the observations at this early stage of the disc's formation could help reveal which of two competing theories of planet formation is correct.

Planets form when matter clumps together in swirling discs of gas and dust, called protoplanetary discs, around infant stars. But many details of how this works are still not known. For example, some scientists think giant planets can form in just a few thousand years, while others argue it takes millions of years.

Now, astronomers led by Dan Watson of the University of Rochester in New York, have gained an unprecedented view of a protoplanetary disc at the young age of just a few hundred thousand years old.

They used the Spitzer Space Telescope to examine the spectrum of infrared light coming from the vicinity of an embryonic star called IRAS 4B, which lies about 1000 light years from Earth.
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Outer cocoon
At this very early stage, an outer cocoon of gas and dust called an envelope still surrounds the star and its swirling disc. Previous observations in the microwave portion of the spectrum suggested that this large cocoon is contracting and sending material onto the disc. But the inner region, where the disc meets the cocoon, could not be seen at these wavelengths.

The Spitzer observations probe this inner region and reveal infrared light emitted by massive amounts of water vapour – the equivalent of five times the content of the Earth's oceans.

The vapour is too hot to be explained by the embryonic star's radiation alone, suggesting another process must be heating it up.

Sonic boom
The team believes ice from the cocoon is pelting the disc at a rate faster than the speed of sound there, creating a shock front. "The sonic boom that it endures when it lands on the disc heats it up very efficiently" and vaporises it.

This supersonic shock "has been searched for and theorised about for decades", Watson says. It is a short-lived phenomenon that only occurs during the first few hundred thousand years of the star and disc formation, while the envelope is still feeding the disc.

The light emitted as the icy particles hit the disc can be used to learn more about the disc itself at this early stage, which could shed light on how planets form.

Turbulent birth
Most astronomers believe planets form according to a model known as "core accretion", in which small particles snowball into larger and larger objects over millions of years.

A competing idea, called "disc instability", is that turbulence in the disc can cause matter to collapse into planets extremely quickly, producing gas giants such as Jupiter in just a few thousand years.

"If you wanted to test between those scenarios, one of the most important places to look would be the stage we're looking at now." Future observations of such young discs could reveal how turbulent the discs are, and thus whether they boast the conditions required for disc instability. "The whole subject of the very beginnings of the development of solar systems is open to study now," Watson says.

Source: The development of a protoplanetary disk from its natal envelope

Stars and Habitable Planets from Solstation
Star system soaked with rain from LiveScience
Protostars by Thomas Green @ American Scientist
Major Planet Forming Mystery Solved from LiveScience

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Tuesday, August 28, 2007

Exploding Lunar Eclipse

Most of us appreciate lunar eclipses for their silent midnight beauty. NASA astronomer Bill Cooke is different: he loves the explosions.
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On Tuesday morning, Aug. 28th, Earth's shadow settled across the Moon for a 90-minute total eclipse: full story. In the midst of the lunar darkness, Cooke tries to record flashes of light - explosions caused by meteoroids crashing into the Moon and blasting themselves to smithereens.

Lunar explosions are nothing new. Cooke's team has been monitoring the Moon since late 2005 and they've recorded 62 impacts so far. "Meteoroids that hit Earth disintegrate in the atmosphere, producing a harmless streak of light. But the Moon has no atmosphere, so 'lunar meteors' plunge into the ground," he says. Typical strikes release as much energy as 100 kg of TNT, gouging craters several meters wide and producing bursts of light bright enough to be seen 240,000 miles away on Earth through ordinary backyard telescopes.

"About half of the impacts we see come from regular meteor showers like the Perseids and Leonids," said team-member Danielle Moser. "The other half are 'sporadic' meteors associated with no particular asteroid or comet."

Read more on "Exploding Eclipse" from NASA


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Monday, August 27, 2007

Warping of Space-Time

Einstein's predicted warping of space-time has been discovered around neutron stars, the most dense observable matter in the universe.

The warping shows up as smeared lines of iron gas whipping around the stars, University of Michigan and NASA astronomers say. The finding also indicates a size limit for the celestial objects.

The same distortions have been spotted around black holes and even around Earth, so while the finding may not be a surprise, it is significant for answering basic questions of physics, said study team member Sudip Bhattacharyya of NASA's Goddard Space Flight Center in Greenbelt, Md. and the University of Maryland, College Park.
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"This is fundamental physics," Bhattacharyya said. "There could be exotic kinds of particles or states of matter, such as quark matter, in the centers of neutron stars, but it's impossible to create them in the lab. The only way to find out is to understand neutron stars."

Neutron stars can pack more than a sun's worth of material into a city-sized sphere. A few cups of neutron-star stuff would outweigh Mount Everest. Astronomers use these collapsed stars as natural laboratories to study how tightly matter can be crammed under the most extreme pressures nature can offer.

To even begin to address the mystery of what lies within these dying stars, scientists must accurately and precisely measure their diameters and masses.

In two concurrent studies, astronomers used the European Space Agency's XMM-Newton X-ray Observatory and the Japanese/NASA Suzaku X-ray to survey three neutron-star binaries: Serpens X-1, GX 349+2 and 4U 1820-30. They also studied the spectral lines from hot iron atoms that whirl around in a disk just beyond the neutron stars' surfaces at speeds reaching 40 percent light speed.

Normally, the measured spectral line for the superheated iron atoms would show up as a symmetrical peak. However, their results showed a skewed peak that was indicative of distortion due to relativistic effects. The extremely fast motion of the gas (and the related powerful gravity), they say, causes the line to smear, shifting it to longer wavelengths.

The measurements allowed them to determine maximum star size. "We're seeing the gas whipping around just outside the neutron star's surface," said XMM-Newton team member Edward Cackett of the University of Michigan. "And since the inner part of the disk obviously can't orbit any closer than the neutron star's surface, these measurements give us a maximum size of the neutron star's diameter. The neutron stars can be no larger than about 20.5 miles (33 kms) across."

Original Source: European Space Agency
XMM-Newton and Suzaku help pioneer method for probing exotic matter

Possible Closest Neutron Star to Earth Found @ Penn State Uni
Dead star found polluted by earthlike planet @ Scientific Blogging
Was the brightest supernova the birth of a quark star? @ NewScientistSpace

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Sunday, August 26, 2007

The MAGIC Telescope

The Magic Telescope - Introduction

Imaging Air Cherenkov Telescopes
IACTs are ground-based telescopes for the detection of very high energy (VHE) electromagnetic particles, in particular gamma rays. Having no electric charge, VHE gammas are not affected by magnetic fields, and can act as messengers of distant cosmic events.

Although high-energy gamma quanta get absorbed in the atmosphere - they can be observed indirectly. The absorption process proceeds by creation of a cascade or shower of high-energy secondary particles.
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Most generally, the observation of gamma rays (electromagnetic radiation of high energy) is one aspect of astroparticle physics.

Astroparticle physics is a new field developing as an intersection of Particle Physics, Nuclear Physics, Astrophysics, Gravitation and Cosmology. One of its cornerstones is Cosmic Ray Physics, which has its origins many decades in the past; then scientists observed in balloons and in mountain top laboratories the many charged particles impinging upon the earth.

Today, the field has substantially widened, and includes all particles. In recent years, activities (and funding) have accelerated, with fundamental discoveries being made at an astonishing frequency. Using the understanding of particle interactions at very high energies, as derived from experiments in accelerator laboratories, the picture of how the universe developed since its earliest beginnings, some ten billion years ago, is changing fast.

Theoretical models fuel multiple experiments, using different particles coming to earth from space.

MAGICs observation of gamma ray bursts from Backreaction
Hints of a breakdown of relativity theory? from Sciam blog posting

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Saturday, August 25, 2007

Pulsing Vortex

Pulsing Vortex by ClintJCL. Click on Image to Enlarge

Watching an Object Go Quantum?
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Build a pendulum small enough, and it may violate Newton's classical laws of mechanics, following quantum rules instead. Researchers hope to observe such violations by cooling a tiny wobbling object to very low temperatures.

A team of theorists has now analyzed a vibrating bar, both classically and quantum mechanically, and predicted the signatures of quantum behavior that experimenters might observe, as they report in the 27 July Physical Review Letters. What's more, the team found that such classical-to-quantum transition is within reach of current technology.

They hope that experiments on small moving objects will soon shed light on a deep question: why do large objects obey classical laws?

Quantum mechanical objects like atoms can act as waves and exhibit other bizarre behaviours, but large objects don't. Researchers have seen a transition from classical to quantum behaviour in some kinds of experiments with larger-than-atomic objects, such as electric currents in tiny wire loops. But they haven't seen it in so-called mechanical systems, where a solid object vibrates or wobbles, except for a single controversial result in 2005.

Most physicists believe that a large object behaves classically because it constantly interacts with its environment. Sufficiently cooling a small object should reduce this interaction and reveal its quantum behaviour.

But some researchers, including Roger Penrose of Oxford University in England, believe that even isolated objects with too much mass will behave classically, thanks to an obscure gravitational effect. The Penrose idea can be tested by observing a small and cold vibrating bar, says Ron Lifshitz of Tel Aviv University in Israel. If quantum behaviour doesn't show up when the bar is cooled below the temperature predicted by conventional quantum mechanics, then Penrose could be right.

When looking for quantum effects in vibrating objects, "most researchers are trying to go directly for holy grails," says Lifshitz. They're looking for exotic effects that might not be observable for years, he says. Instead, his team simply calculated the first signatures of a transition from classical to quantum behavior as the mass and temperature of a vibrating object decrease.

The researchers considered a suspended elastic beam, or nanowire, that is held at both ends and is given periodic pushes by an outside source. The nanowire is a so-called nonlinear resonator and behaves somewhat differently from an ordinary oscillating spring or pendulum. For example, classically, it usually oscillates at one of two amplitudes, depending on initial conditions.

The team calculated the behaviour of the resonator, according to both classical and quantum laws, for three different situations: a resonator isolated from the environment, a resonator in contact with an environment at absolute zero temperature, and a resonator in contact with an environment at a low temperature.

For the low temperature case, the researchers chose a temperature at which the classical resonator is restricted to the two states of motion and cannot switch between them. They found that according to quantum rules the resonator can spontaneously switch states or occupy states in between. Experimentalists cooling the resonator could watch for changes in the oscillation amplitude--a clear sign of a transition to quantum behavior.

According to the study, a nanowire with a mass of about 10-21 kilograms will show signs of the transition at a temperature of about 10 millikelvin. Lifshitz expects the results to be verified in the next few years.

Although the prospect of observing quantum signatures in a nanomechanical system is exciting to Miles Blencowe of Dartmouth University in Hanover, New Hampshire, he says it will be difficult. "After all, we have yet to observe a genuine quantum signature of any larger than molecular mechanical system." On the other hand, if it works, says Blencowe, "then we will be a little more certain that quantum mechanics extends up to the macroscopic domain."

Watching an Object Go Quantum - Katie McAlpine
Katie McAlpine is an intern writer at APS.

It's a Trick of the Light. Reality is relative.
Your reality is Real to You. Be Master of your reality.


Thursday, August 23, 2007

Gaping hole in the Universe

There may be an enormous hole in the Universe, nearly a billion light-years across, empty of any matter such as stars, galaxies and gas. While earlier studies have shown holes, or voids, in the large-scale structure of the Universe, this new discovery dwarfs them all.

The region had been dubbed the "WMAP Cold Spot," because it stood out in a map of the Cosmic Microwave Background (CMB) radiation made by the WMAP satellite, launched by NASA in 2001. The CMB, faint radio waves that are the remnant radiation from the Big Bang, is the earliest "baby picture" available of the Universe. Irregularities in the CMB show structures that existed only a few hundred thousand years after the Big Bang.

"Although our surprising results need independent confirmation, the slightly lower temperature of the CMB in this region appears to be caused by a huge hole devoid of nearly all matter roughly 6-10 billion light-years from Earth," said Lawrence Rudnick astronomy professor at the University of Minnesota .
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How does a lack of matter cause a lower temperature in the Big Bang's remnant radiation as seen from Earth?

The answer may lie in dark energy, which became a dominant force in the Universe very recently, when the Universe was already three-quarters of the size it is today. Dark energy works opposite gravity and is speeding up the expansion of the Universe.

CMB photons that pass through a large void just before arriving at Earth have less energy than those that pass through an area with a normal distribution of matter in the last leg of their journey.

In a simple expansion of the universe, without dark energy, photons approaching a large mass -- such as a supercluster of galaxies -- pick up energy from its gravity. As they pull away, the gravity saps their energy, and they wind up with the same energy as when they started.

But photons passing through matter-rich space when dark energy became dominant don't fall back to their original energy level. Dark energy counteracts the influence of gravity and so the large masses don't sap as much energy from the photons as they pull away. Thus, these photons arrive at Earth with a slightly higher energy, or temperature, than they would in a dark energy-free Universe.

Conversely, photons passing through a large void experience a loss of energy. The acceleration of the Universe's expansion, and thus dark energy, were discovered less than a decade ago. The physical properties of dark energy are unknown, though it is by far the most abundant form of energy in the Universe today. Learning its nature is one of the most fundamental current problems in astrophysics.

Astronomers Find Gaping Hole In The Universe
Source: University of Minesotta.

Illustration of the effect of intervening matter in the cosmos on the cosmic microwave background (CMB). On the right, the CMB is released shortly after the Big Bang, with tiny ripples in temperature due to fluctuations in the early Universe. As this radiation traverses the Universe, filled with a web of galaxies, clusters, superclusters and voids, it experiences slight perturbations. In the direction of the giant newly-discovered void, the WMAP satellite (top left) sees a cold spot, while the VLA (bottom left) sees fewer radio galaxies. (Credit: Bill Saxton, NRAO/AUI/NSF, NASA)

Dark Energy paints the Void? from Centauri Dreams
WMAP Cold Spot - Mostly Empty Space - by Pamela @ Star Stryder
Critique on NRAO illustration by Ryan Wyatt @ Visualizing Science

Wednesday, August 22, 2007

The Sky in Google Earth

Believe it or not The Next Generation will be able to name the Galaxies and Stars in the Universe, just like we could name the major cities, capitals and nations (states) on Earth.

The wonders of modern technology Google and cheap Internet mean the volume of online information available on whatever subject or topic takes their interest, is almost unlimited - one would need more than a lifetime to digest just a fraction, but it will certainly make virtual space travel educational, entertaining and fun.
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HAWK-I Takes Off

Europe's flagship ground-based astronomical facility, the ESO VLT, has been equipped with a new 'eye' to study the Universe.

Source New Wide Field Near-Infrared Imager for ESO's Very Large Telescope

Monday, August 20, 2007

Super Massive Super Hot

NASA's Spitzer Space Telescope shows that supermassive black holes at the centers of elliptical galaxies keep the galactic "thermostat" so high gas cannot cool, stunting the birth of new stars.

Astronomers have detected dust grains mingling with blazing hot gas at temperatures of 10 million degrees Kelvin (10 million Celsius) or 17 million Fahrenheit, in an area surrounding the elliptical-shaped galaxy called NGC 5044.

Similar to raindrops forming in Earth's clouds, stars form when dense cosmic clouds of gas and dust condense. Scientists suspect that if the gas surrounding a galaxy never cools enough to condense, then new stars cannot form.

Galaxies in the universe come in many shapes and sizes. Spiral galaxies, like the Milky Way, are usually active in star formation.

By contrast, elliptical galaxies are stellar retirement communities because they are made up of older stars, and don't form many new stars. Many elliptical galaxies, like NGC 5044, are found at the centers of galaxy clusters that are filled with enormous amounts of hot gas. Why the gas doesn't cool and form new stars is a subject of intense debate among astronomers.
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Feedback heating

Observations with NASA's Hubble Space Telescope have shown small, massive clouds of dusty gas near the cores of many elliptical galaxies. Astronomers think these clouds may play a crucial role in feedback heating. They suspect this material probably gravitated toward the galaxy's center after being ejected by nearby dying stars, as part of their normal life cycle.

When some of this dusty gas approaches the host galaxy's central supermassive black hole, a large amount of energy is released -- enough to heat nearby gas to extremely high temperatures, making it buoyant. Like smoke carrying ashes away from a fire, scientists believe that this buoyant gas floats away from the galaxy's center carrying some dust with it. As plumes of this dusty smoke fill the galaxy's surrounding area, gas around the galaxy is also heated. Temi's team was the first to see this cosmic smoke with Spitzer's super-sensitive infrared eyes.

Whenever the central back hole takes another gulp of the dusty gas hovering around the galaxy's center, enough energy will be fed back to heat up more of the surrounding gas, and feedback heating will happen all over again, maintaining the temperature of the surrounding gas. Both the heating and buoyant removal of gas from the galaxy's center reduces the likelihood of star formation.

Astronomers have long hypothesized about feedback heating in the hot cluster gas surrounding elliptical galaxies, but Spitzer has given us the first piece of observational evidence that this might actually be occurring in elliptical galaxies across the universe.

Original Source: Do Supermassive Black Holes Stunt Stellar Birth in Galaxies?
by Linda Vu, Spitzer Science Center.


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Sunday, August 19, 2007

Angel Wings & hidden fields

Click Image to Enlarge.- Image by Roger Johnston @ techrepublic

Though we have discovered most of the constituent part-icles that make up the Universe, the very thing that gives matter mass - the very stuff that we and everything is 'made' off - still eludes us.

The Higgs boson, a fundamental particle predicted by theorist Peter Higgs, may be the key to understanding why elementary particles have mass. The vacuum — or empty space — is far from empty.
Empty Space is "noisy" and full of virtual particles and force fields. The origin of mass seems to be related to this phenomenon.

In Einstein's theory of relativity, there is a crucial difference between massless and massive particles: All massless particles must travel at the speed of light, whereas massive particles can never attain this ultimate speed. But, how do massive particles arise?

Higgs proposed that the vacuum contains an omnipresent field that can slow down some (otherwise massless) elementary particles — like a vat of molasses slowing down a high-speed bullet.

Such particles would behave like massive particles travelling at less than light speed. Other particles — such as the photons of light — are immune to the field: they do not slow down and remain massless.

Hunt for the Higgs from International Science Grid

Although the Higgs field is not directly measurable, accelerators can excite this field and "shake loose" detectable particles called Higgs bosons. So far, experiments using the world's most powerful accelerators have not observed any Higgs bosons, but indirect experimental evidence suggests that particle physicists are poised for a profound discovery.

Welcome to CERN - The World's largest Particle Physics Lab

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Friday, August 17, 2007

Cosmic Mystery Deepens

The difficulties trying to fathom and understand what we detect and observe or see billions of light years away.

Abell 520 in the Constellation of Orion some 2.4 billion light years away, where astronomers have discovered a chaotic scene unlike any witnessed before in a collision between giant galaxy clusters. The results challenge our understanding of the way clusters merge, they possibly make us even reexamine the nature of dark matter itself.

There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects.
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Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas.

A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster.

However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea (Hawaii), a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies.

In the Bullet Cluster, the hot gas is slowed down during the collision but the galaxies and dark matter appear to continue on unimpeded. In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas.

While the components of Abell 520 - galaxies, hot gas, and dark matter - are found in unexpected places, the overall amount of these components totals what scientists expect.

The results lead to two possible explanations: one involving how galaxy clusters interact, and the other about the nature of dark matter itself. Both of these explanations would pose uncomfortable problems for current prevailing theories.

The first option is that the galaxies were separated from the dark matter through a complex set of gravitational "slingshots." This explanation is problematic because computer simulations have not been able to produce slingshots that are nearly powerful enough to cause such a separation.

The second option is that dark matter is affected not only by gravity, but also by an as-yet-unknown interaction between dark matter particles. This exciting alternative would require new physics and could be difficult to reconcile with observations of other galaxies and galaxy clusters, such as the aforementioned Bullet Cluster.

X-ray: NASA/CXC/UVic./A.Mahdavi et al. Optical/Lensing: CFHT/UVic./A.Mahdavi et al.


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Wednesday, August 15, 2007

Star Streaks Across The Sky

A new ultraviolet mosaic from NASA's Galaxy Evolution Explorer shows an amazingly long comet-like tail behind a star streaking through space at supersonic speeds. The star, named Mira after the Latin word for "wonderful," has been a favorite of astronomers for about 400 years. It is a fast-moving, older star called a red giant that sheds massive amounts of surface material.

The space-based Galaxy Evolution Explorer scanned the popular star during its ongoing survey of the entire sky in ultraviolet light. Astronomers then noticed what looked like a comet with a tail. In fact, material blowing off Mira is forming a wake 13 light-years long, or about 20,000 times the average distance of Pluto from the sun. Nothing like this has ever been seen before around a star.

As Mira hurtles along, its tail sheds carbon, oxygen and other important elements needed for new stars, planets and possibly even life to form. This tail material, visible now for the first time, has been released over the past 30,000 years.
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Billions of years ago, Mira was similar to our sun. Over time, it began to swell into what's called a variable red giant - a pulsating, puffed-up star that periodically grows bright enough to see with the naked eye. Mira will eventually eject all of its remaining gas into space, forming a colorful shell called a planetary nebula. The nebula will fade with time, leaving only the burnt-out core of the original star, which will then be called a white dwarf.

Compared to other red giants, Mira is traveling unusually fast, possibly due to gravitational boosts from other passing stars over time. It now plows along at 130 kilometers per second, or 291,000 miles per hour. Racing along with Mira is a small, distant companion thought to be a white dwarf. The pair, also known as Mira A (the red giant) and Mira B, orbit slowly around each other as they travel together in the constellation Cetus 350 light-years from Earth.

In addition to Mira's tail, Galex also discovered a bow shock, a type of buildup of hot gas, in front of the star, and two sinuous streams of material coming out of the star's front and back. Astronomers think hot gas in the bow shock is heating up the gas blowing off the star, causing it to fluoresce with ultraviolet light. This glowing material then swirls around behind the star, creating a turbulent, tail-like wake. The process is similar to a speeding boat leaving a choppy wake, or a steam train producing a trail of smoke.

The fact that Mira's tail only glows with ultraviolet light might explain why other telescopes have missed it. The Galaxy Evolution Explorer is very sensitive to ultraviolet light and also has an extremely wide field of view, allowing it to scan the sky for unusual ultraviolet activity.

Mira's tail offers a unique opportunity to study how stars like our sun die and ultimately seed new solar systems.

"It's amazing to discover such a startlingly large and important feature of an object that has been known and studied for over 400 years," said James D. Neill of Caltech. "This is exactly the kind of surprise that comes from a survey mission like the Galaxy Evolution Explorer."

"This is an utterly new phenomenon to us, and we are still in the process of understanding the physics involved," said Mark Seibert of the Observatories of the Carnegie Institution of Washington in Pasadena. "We hope to be able to read Mira's tail like a ticker tape to learn about the star's life."

Mira is also what's called a pulsating variable star. It dims and brightens by a factor of 1,500 every 332 days, and will become bright enough to see with the naked eye in mid-November 2007. Because it was the first variable star with a regular period ever discovered, other stars of this type are often referred to as "Miras."

Mira is located 350 light-years from Earth in the constellation Cetus, otherwise known as the whale. Coincidentally, Mira and its "whale of a tail" can be found in the tail of the whale constellation.

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. Caltech manages JPL for NASA. The mission was developed under NASA's Explorers Program managed by NASA's Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.

Speeding-Bullet Star Leaves Enormous Streak Across Sky JPL News Release
Graphics & information about the Galaxy Evolution Explorer are online at - and -
Mira: Star with a Comet-like Tail from Centauri Dreams
Shocking Mira and Bowshocks by Julianne @ Cosmic Variance
Mira's Supersonic Comet Tail Across The Sky @ Scientific Blogging
Star light, star bright: - FSU duplicating conditions of supernovas.


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Tuesday, August 14, 2007

Hot Gas in Space Mimics Life

Electrically charged specks of interstellar dust organize into DNA-like double helixes and display properties normally attributed to living systems, such as evolving and reproducing.

But scientists are hesitant to call the dancing dust particles "alive," and instead say they are just another example of how difficult it is to define life.
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Plasma life

The computer model, detailed in the Aug. 14 issue of the New Journal of Physics, shows what happens to microscopic dust particles when they are injected into plasma.

Plasma is the fourth state of matter along with solids, liquids and gases. While unfamiliar to most people, plasma is the most common phase of matter in the universe. Stars are luminous balls of plasma, and diffuse plasma pervades the space between stars. Plasma forms when gas becomes so hot that electrons are stripped from atomic nuclei, leaving behind a soup of charged particles.

Past studies on Earth have shown that if enough particles are injected into a low-temperature plasma, they will spontaneously organize into crystal-like structures.

The new computer simulations suggest that in the gravity-free environment of space, the plasma particles will bead together to form string-like filaments that then twist into corkscrew shapes. The helical strands resemble DNA and are themselves electrically charged and attracted to one another.

The computer-modeled plasma particles can also divide to form two copies of the original structure and even "evolve" into more stable structures that are better able to survive in the plasma.

"These complex, self-organized plasma structures exhibit all the necessary properties to qualify them as candidates for inorganic living matter," said study team member V.N. Tsytovich of the Russian Academy of Science.

Is it alive?

Nevertheless, Tsytovich's colleague and study team member, Gregor Morfill of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, is hesitant to call the plasma particles alive.

"Maybe it's a question of upbringing," Morfill said. "I would hesitate to call it life. The reason why we published this paper is not because we wanted to suggest this could evolve into life, but because we wanted to start the discussion ... once more of what exactly do we mean by life."

Seth Shostak, a senior astronomer at the SETI Institute in Mountain View, California, also was cautious in calling the particles alive. The facts are, we still don't have a good definition of what 'life' is.

Shostak points out that while most high-school biology textbooks include as requirements for life the ability to metabolize and reproduce, it's easy to think of things that break these rules. Fire, for example, reproduces and metabolizes, but most people would not say it is alive; and mules, which are clearly alive, can't reproduce.

"We still stumble on what it means to be alive, and that means that these complex molecules are in a never-never land between the living and the merely reacting," Shostak added.

If the particles were considered alive though, Shostak said, it would completely overturn another common assumption about life.

"We've always assumed that life was a planetary phenomenon. Only on planets would you have the liquids thought necessary for the chemistry of life," he said. "So if you could have life in the hot gases of a star, or in the hot, interstellar gas that suffuses the space between the stars, well, not only would that be 'life as we don't know it' but it might be the most common type of life."

Hot Gas in Space Mimics Life
By Ker Than from
Life's Cometary Arrival Unlikely by Centauri Dreams
Life on Comets? - New Theory from Cardiff University
Physicists Discover Dust With Lifelike Qualities from Science Daily


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Monday, August 13, 2007

Stellar Debris N49

This is a composite image of N49, the brightest supernova remnant in optical light in the Large Magellanic Cloud.

The Chandra X-ray image (blue) shows million-degree gas in the center. Much cooler gas at the outer parts of the remnant is seen in the infrared image from Spitzer (red). While astronomers expected that dust particles were generating most of the infrared emission, the study of this object indicates that much of the infrared is instead generated in heated gas.

The unique filamentary structure seen in the optical image by Hubble (white & yellow) has long set N49 apart from other well understood supernova remnants, as most supernova remnants appear roughly circular in visible light. Recent mapping of molecular clouds suggests that this supernova remnant is expanding into a denser region to the southeast, which would cause its asymmetrical appearance. This idea is confirmed by the Chandra data. Although X-rays reveal a round shell of emission, the X-rays also show brightening in the southeast, confirming the idea of colliding material in that area.

N49 is about 160,000 light years (distance to Large Magellanic Cloud) in the Dorado Constellation

Credit X-ray: NASA/CXC/Caltech/S.Kulkarni et al.; Optical: NASA/STScI/UIUC/Y.H.Chu & R.Williams et al.; IR: NASA/JPL-Caltech/R.Gehrz et al.
More Images of N49 and Zoom into N49 with Chandra
Supernovas & Supernova Remnants from Chandra X-Ray Observatory
Taking it to the Edge RCW 86 & G347.3-0.5 Chandra & XMM Newton X-Ray Images

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Friday, August 10, 2007

Supernova factory

The largest known swarm of red supergiant stars has been found near the central bulge of our galaxy. It offers a rare glimpse of massive stars on the verge of exploding.

Red supergiants are among the largest stars in the universe – and in fact are second in size only to rare 'hypergiant' stars such Eta Carinae. Spanning several hundred times the diameter of the Sun, each could fit millions of Sun-like stars inside it.

These stellar titans are extremely rare. Only very massive stars, more than 10 times as heavy as the Sun, turn into red supergiants. And the red supergiant phase lasts just 100,000 years before ending in a supernova, a fleeting moment compared to the overall lifespan of the star
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Only about 200 red supergiants have been identified in our galaxy.
In 2006, a team led by Don Figer of the Rochester Institute of Technology (RIT) in New York, NY, US, reported finding a massive cluster of thousands of stars that included 14 red supergiants – the biggest collection of these rare stars then known.
Now, Ben Davies, also of RIT, and a team that includes Figer have identified an even larger group of 26 red supergiants.

'Supernova factory'
The stars were revealed to have the characteristic light spectrum of red supergiants by the Keck II telescope atop Mauna Kea in Hawaii. The cluster has been named RSGC2, and contains about 50,000 stars, making it one of the largest clusters of young stars in the galaxy. The team believes the cluster is less than 20 million years old.

The masses of the supergiants in the cluster are uncertain, but the brightest among them is 300,000 times as luminous as the Sun. RSGC2 was found just a few hundred light years from the one found in 2006, called RSGC1, and the two are very similar in age.

The close proximity of the two massive clusters is probably not a coincidence. There are other signs of copious star formation in their vicinity, a region where one of the galaxy's spiral arms, called Scutum-Crux, meets the central bulge of the galaxy.

"There might be something to do with the physical conditions there where they meet that makes it ripe for forming stars and forming massive clusters," Davies said.

The two red supergiant clusters provide a rare opportunity to study the properties of stars that are very close to exploding.

Ben Davies, Don F.Figer, R. Kudritzki et al., 2007: 'A massive cluster of Red Supergiants at the base of the Scutum-Crux arm' -- accepted to ApJ


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Wednesday, August 08, 2007

Siblings in Serpens Cloud

A spectacular new image from NASA's Spitzer Space Telescope uncovers a small group of young stellar "siblings" in the southern portion of the Serpens cloud

located approximately 848 light-years away from Earth.

Scientists suspect that this discovery will lead them to more clues about how these cosmic families, which contain hundreds of gravitationally bound stars, form and interact.

"It's amazing how these stars really stand out in the Spitzer images. At visible wavelengths the stars can't be seen at all; they are completely obscured by the dust in the cloud," says Robert Gutermuth, of the Harvard-Smithsonian Center for Astrophysics. "This is the first time that anyone has ever seen these stars."
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Spitzer uncovered the young star cluster, but couldn’t determine whether they are forming a new "family unit," or are members of an established stellar "clan." In the case of Serpens South, Dr. Tyler Bourke, also of the Harvard-Smithsonian Center for Astrophysics, used the Smithsonian’s Submillimeter Array (SMA) to solve this mystery of stellar ancestry.

From the ground, he measured motions of the gas surrounding the newly formed cluster, and determined that the newly discovered stars belonged to the Serpens star-forming cloud, which also hosts the famous and massive Serpens star cluster.

“With the SMA, we were able to show that Serpens South is moving at the same speed as the Serpens Cluster,” said Bourke. “It looks like the smaller families are sticking together.”

In the Spitzer photograph, the newly discovered Serpens South stars are shown as green, yellow, and orange specks, sitting atop a black line that runs through the middle of the image. The "line" is a long, dense patch of cosmic dust and gas, which is currently condensing to form stars. Like raindrops, stars form when thick cosmic clouds collapse.

Tints of green represent hot hydrogen gas. Spitzer can see this hydrogen gas "fingerprint" when the high-speed jets shooting out of the young stars violently collide with cool gas in the surrounding cloud.

"This image provides just a taste of the exciting science that will come from the Gould's Belt Legacy project," says Lori Allen of the Harvard-Smithsonian Center for Astrophysics, principal investigator of the Gould’s Belt Legacy program, which discovered the Serpens South Cluster.

For years, astronomers have debated how members of large stellar families, which can contain hundreds of stars, are related. Some astronomers suspect that the stars may be "fraternal siblings" – born at the same time from the same "parent" cloud of gas and dust. Meanwhile, other scientists suspect that these stellar family members are "adopted" – meaning the stars are born in small batches of a few at a time, and eventually many of these small stellar groups will "bond" to form a massive star cluster, or family.

According to Allen, one of the greatest challenges in determining how a cluster's stars are related is finding the smaller, younger star clusters in the first place.

"Spitzer is currently the only telescope with the capabilities to find young star clusters like Serpens South, which are deeply embedded inside giant cosmic clouds of gas and dust," says Allen.

Source CfA Two Telescopes Combine to Probe Young “Family” of Stars

Dust Cloud Sheds Light on Stellar Brightness Phenomenon from Live Science

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Monday, August 06, 2007

Quad Galaxy Collision

One of the biggest galaxy collisions ever observed is taking place at the centre of this image from Spitzer.
The four white blobs in the middle are large galaxies that have begun to tangle and ultimately merge into a single gargantuan galaxy.

The whitish cloud around the colliding galaxies contains billions of stars tossed out during the messy encounter. Other galaxies and stars appear in yellow, orange and red hues. Blue shows hot gas that permeates this distant region of tightly packed galaxies.

NASA's Spitzer Space Telescope serendipitously spotted the quadruple merger during a routine survey of a distant galaxy cluster, called CL0958+4702, located nearly 5 billion light years away.

Spitzer's infrared eyes observed an unusually large fan-shaped plume of light emerging from a gathering of four elliptical galaxies. Three of the galaxies are about the size of the Milky Way, while the fourth is three times as large.
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The plume turned out to be billions of elderly stars ejected and abandoned during the clash. About half of the stars in the plume will later fall back into the galaxies.

Spitzer observations also show that, unlike most known mergers, the galaxies involved in the quadruple collision are bereft of gas, the source material that fuels star birth. As a result, astronomers predict relatively few new stars will be born in the new, combined galaxy.

Artist's concept showing what the night sky might look like from a hypothetical planet around a star tossed out of an ongoing four-way collision between big galaxies.

Credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA

Galactic Collisions Set Quasars Ablaze from Universe Today
Astronomers Spot Brightest Galaxies in the Distant Universe CfA
First Light for World's Largest 'Thermometer Camera' ESO release

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Sunday, August 05, 2007

NASA's Endeavour launch

National Aeronautics and Space Administration announced the launch countdown schedule for space shuttle Endeavour.

NASA delays launch of Endeavour by 24 hours because of unexpected work to resolve an air leak in the crew cabin. Engineers installed a replacement valve taken from the space shuttle Atlantis. Lift off is now set for the evening of Wednesday 8th August.
The launch window lasts 5 minutes.

During the 11-day mission to the ISS International Space Station, Endeavour's crew will add another truss segment to the expanding station, install a gyroscope and add an external spare parts platform.

The flight will also include at least three spacewalks and will debut a new system that enables docked shuttles to draw electrical power from the station to extend visits to the outpost. If the system functions as expected, three days will be added to the mission.

The STS-118 mission is the 119th space shuttle flight, the 20th flight for Endeavour and the 22nd U.S. flight to the ISS. The mission would be Endeavour's first flight in more than four years.
Space Shuttle Endeavour's Cargo from Space Com
Nuclear fusion could power NASA spacecraft in two decades from Goldenship
The European Space Agency's DARWIN proposals online from Centauri Dreams

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Saturday, August 04, 2007

Phoenix Mars Mission

NASA's Phoenix Mars Mission blasted off Saturday, aiming for a May 25, 2008, arrival at the Red Planet and a close-up examination of the surface of the northern polar region.

Perched atop a Delta II rocket, the spacecraft left Cape Canaveral Air Force Base at 5:26 a.m. Eastern Time into the predawn sky above Florida's Atlantic coast.
Phoenix Mars Mission @ Arizona Education
NASA Phoenix Mission, going to the artic planes of Mars

Wednesday, August 01, 2007

Uncovering the Veil Nebula

The Veil Nebula from Vimeo. Click on arrows for full screen view.

When a star significantly heavier than our Sun runs out of fuel, it collapses and blows itself apart in a catastrophic supernova explosion. A supernova releases so much light that it can outshine a whole galaxy of stars put together.

The exploding star sweeps out a huge bubble in its surroundings, fringed with actual stellar debris along with material swept up by the blast wave. This glowing, brightly-coloured shell of gas forms a nebula: a supernova remnant. Such a remnant can remain visible long after the initial explosion fades away.

Scientists estimate that the supernova explosion occurred some 5000 to 10 000 years ago and could have been witnessed and recorded by ancient civilizations. These would have seen a star increase in brightness to roughly the brightness of the crescent Moon.
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A series of three new images taken with the NASA/ESA Hubble Space Telescope reveals magnificent sections of one of the most spectacular supernova remnants in the sky - the Veil Nebula. The entire shell spans about 3 degrees, corresponding to about 6 full Moons. The small regions captured in the new Hubble images provide stunning close-ups of the Veil. Fascinating smoke-like wisps of gas are all that remain visible of what was once a Milky Way star.

The intertwined rope-like filaments of gas in the Veil Nebula result from the enormous amounts of energy released as the fast-moving debris from the explosion ploughs into its surroundings and creates shock fronts. These shocks, driven by debris moving at 600 000 kilometres per hour, heat the gas to millions of degrees. It is the subsequent cooling of this material that produces the brilliantly coloured glows.

Like the larger scale ground-based observations, the high-resolution Hubble images display two characteristic features: sharp filaments and diffuse emission. These correspond to two different viewing geometries: sharp filaments correspond to an edge-on view of a shock front, and diffuse emission corresponds to a face-on view.

The Hubble images of the Veil Nebula are striking examples of how processes that take place hundreds of lightyears away can sometimes resemble effects we see around us in our daily life. The structures have similarities to the patterns formed by the interplay of light and shadow on the bottom of a swimming pool, rising smoke or ragged cirrus clouds.

Supernovae are extremely important for understanding our own Milky Way. Although only a few stars per century in our Galaxy will end their lives in this spectacular way, these explosions are responsible for making all chemical elements heavier than iron in the Universe. Many elements, such as copper, mercury, gold, iodine and lead that we see around us here on Earth today were forged in these violent events thousands of millions of years ago.
The expanding shells of supernova remnants were mixed with other material in the Milky Way and became the raw material for new generations of stars and planets.

The chemical elements that constitute the Earth, the planets and animals we see around us - and as a matter of fact our very selves - were built deep inside ancient stars and in the supernova explosions that result in the nebula we are seeing here. The green in the grass and the red of our blood are indeed the colours of stardust.

Also known as Cygnus Loop, the Veil Nebula is in the constellation of Cygnus, the Swan, about 1500 lightyears away from Earth.

Wide-field ground-based photo of the Veil Nebula
Image credit & copyright: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: J. Hester (Arizona State University)


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