Monday, July 30, 2007

New Type of Active Galaxy

Image credit: Aurore Simonnet, Sonoma State University.

This illustration shows the different features of an active galactic nucleus (AGN), and how our viewing angle determines what type of AGN we observe. The extreme luminosity of an AGN is powered by a supermassive black hole at the center. Some AGN have jets, while others do not.
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Japanese and NASA Satellites Unveil New Type of Active Galaxy

Active Galactic Nuclei AGN, the extraordinarily energetic cores of galaxies such as Quasars, Blazars, and Seyfert galaxies, powered by accreting supermassive black holes, are among the most luminous objects in our Universe, often pouring out the energy of billions of stars from a region no larger than our solar system.

By using Swift and Suzaku, a team of astronomers has discovered that a relatively common class of AGN escaped detection…until now. These objects are so heavily shrouded in gas and dust that virtually no light gets out.

Evidence for this new type of AGN began surfacing over the past two years. Using Swift’s Burst Alert Telescope (BAT), a team led by Tueller has found several hundred relatively nearby AGNs that were previously missed because their visible and ultraviolet light was smothered by gas and dust. The BAT was able to detect high-energy X-rays from these heavily blanketed AGNs because, unlike visible light, high-energy X-rays can punch through thick gas and dust.

According to popular models, AGNs are surrounded by a donut-shaped ring of material, which partially obscures our view of the black hole. Our viewing angle with respect to the donut determines what type of object we see.
But team member Richard Mushotzky, also at NASA Goddard, thinks these newly discovered AGN are completely surrounded by a shell of obscuring material.

Another possibility is that these AGN have little gas in their vicinity. In other AGN, the gas scatters light at other wavelengths, which makes the AGN visible even if they are shrouded in obscuring material. The results imply that there must be a large number of yet unrecognized obscured AGNs in the local universe.

In fact, these objects might comprise about 20 percent of point sources comprising the X-ray background, a glow of X-ray radiation that pervades our Universe. NASA’s Chandra X-ray Observatory has found that this background is actually produced by huge numbers of AGNs, but was unable to identify the nature of all the sources.

By missing this new class, previous AGN surveys were heavily biased, and thus gave an incomplete picture of how supermassive black holes and their host galaxies have evolved over cosmic history.

"We think these black holes have played a crucial role in controlling the formation of galaxies, and they control the flow of matter into clusters," says Tueller. "You can’t understand the universe without understanding giant black holes and what they’re doing."

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Friday, July 27, 2007

Sun shakes Earth's Magnetic Field

Killer electrons from Vimeo. Click on arrows for full screen view

ESA's Cluster Mission helps reveal how the Sun shakes the Earth's magnetic field.

Space is a hostile region for astronauts & satellites. One constituent of this hazardous environment around the Earth are very energetic electrons, able to perturb or permanently damage satellites.

Ultra Low Frequency (ULF) waves, which travel along the Earth's magnetic field lines, are a prime candidate for generating these killer electrons, but the source of these waves remains unclear.
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A recent study using ground based instrumentation and a dozen satellites at a range of altitudes, provides a means to trace the energy source of these waves from the solar wind into the Earth's magnetosphere down to the ground.

Part of this satellite constellation, the four spacecraft of the ESA Cluster mission, was located at the border of the magnetosphere and played a major role in discriminating between the various theoretical ULF wave generation scenarios.

Quasi-sinusoidal oscillations of the magnetic field lines with periods of a few minutes were recorded continuously for several hours,
as if a celestial musician had plucked the magnetic field lines or strings of the Earth's magnetic guitar

Several ways of exciting these waves have been proposed. Most of them involve the solar wind as the external driver. The solar wind is a continuous stream of solar particles impacting and shaping the Earth's magnetic environment. However, understanding the global nature of these geomagnetic pulsations and the tracing of the energy transfer from the solar wind to the ground is a difficult task.

It requires a fortuitous alignment of several satellites, together with ground–based instruments to observe the oscillations simultaneously.

More from ESA releases
A space armada and ground based instruments to track ULF waves
Image & Simulation Credit: Andy Kale, University of Alberta
'Killer' electrons in orbit explained by Heather Catchpole @ Cosmos Magazine
Killer Electrons In Space Are Now Less Mysterious from Science Daily releases


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Wednesday, July 25, 2007

Matter at Ultra Speed

The REM Telescope courtesy of P Aniol. ESO Release.

Matter Flashed at Ultra Speed

Astronomers using REM have for the first time measured the velocity of the explosions known as gamma-ray bursts (GRBs). The material is travelling at the extraordinary speed of more than 99.999% of the velocity of light, the maximum speed limit in the Universe.
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Gamma Ray Burts are short flashes of energetic gamma-rays lasting from less than a second to several minutes. They release a tremendous quantity of energy in this short time making them the most powerful events since the Big Bang. They come in two different flavours, long and short ones. Over the past few years, international efforts have convincingly shown that long GRBs are linked with the ultimate explosion of massive stars (hypernovae) while the short ones most likely originate from the violent collision of neutron stars and/or black holes . Irrespective of the original source of the GRB energy, the injection of so much energy into a confined volume will cause a fireball to form. Gamma-ray photons have nearly a million times more energy than the 'visual' photons the eye can see.

On 18 April and 7 June 2006, the NASA/PPARC/ASI Swift satellite detected two bright gamma-ray bursts. In a matter of a few seconds, their position was transmitted to the ground, and the REM telescope began automatically to observe the two GRB fields, detecting the near-infrared afterglows, and monitored the evolution of their luminosity as a function of time (the light curve).

The gamma-ray bursts were located 9.3 and 11.5 billion light-years away, respectively. For both events, the afterglow light curve initially rose, then reached a peak, and eventually started to decline, as is typical of GRB afterglows.

The peak is, however, only rarely detected. Its determination is very important, since it allows a direct measurement of the expansion velocity of the explosion of the material.

For both bursts, the velocity turns out to be very close to the speed of light, precisely 99.9997% of this value. Scientists use a special number, called the Lorentz factor, to express these high velocities. Objects moving much slower than light have a Lorentz factor of about 1, while for the two GRBs it is about 400.

While single particles in the Universe can be accelerated to still larger velocities - one has to realise that in the present cases, it is the equivalent of about 200 times the mass of the Earth that acquired this incredible speed.

"You certainly wouldn't like to be in the way"
"The next question is which kind of 'engine' can accelerate matter to such enormous speeds," said Stefano Covino.

Notes. Strictly speaking, the Lorentz factor is the ratio between the total and rest-mass energy of the fireball.
REM (Rapid Eye Mount) is a small (60 cm mirror diameter) rapid reaction automatic telescope dedicated to monitor the prompt afterglow of Gamma Ray Burst events. It is located at the ESO La Silla Observatory in Chile.

REM Measures Speed of Material Ejected in Cosmic Death from ESO
VLT Automatically Takes Detailed Spectra of Gamma-Ray Burst Afterglows
Pierre Auger Observatory & GZK cutoff - by Stefan @ BackReaction.
Chandra captures Supermassive Black Holes in 'younger' Galaxies


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Tuesday, July 24, 2007

Close Stellar Encounters

lopsided debris disk around a young star known as HD 15115.

Using the Hubble Space Telescope and W. M. Keck Observatory astronomers have found a lopsided debris disk around a young star known as HD 15115.As seen from Earth, the edge-on disk resembles a needle sticking out from the star.

Astronomers think the disk's odd imbalanced look is caused by dust following a highly elliptical orbit about the star. The lopsided disk may have been caused by the gravity of planets sweeping up debris in the disk or by the gravity of a nearby star.
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Debris disks are produced by dust from collisions among protoplanetary bodies, which are the building blocks of planets. These dusty disks can be affected by planets nearer to the star, much as Jupiter's gravity affects asteroids in the asteroid belt.

This discovery is consistent with models for planetary upheavals in our own solar system, where Neptune may have originally formed between Saturn and Uranus. Neptune was eventually kicked out to its present location by a gravitational dance between Saturn and Jupiter before their orbits stabilized. "Therefore, we speculate that if such a planetary upheaval were occurring around HD 15115 at the present time, it could explain the highly asymmetric disk," said Paul Kalas from the University of California at Berkeley.

This might happen through a powerful gravitational interaction between planets that kicks one or more planets into highly elliptical orbits, or even ejects them into interstellar space. When the planet's orbit becomes elliptical through a violent upheaval, the rest of the disk can be disturbed into an elliptical shape, according to Kalas.

Kalas also is studying whether the gravity of a star known as HIP 12545, located about 10 light-years from HD 15115, may have created the disk's lopsided shape due to a close encounter in the past.

Dusty disks are known to exist around at least 100 stars, but because of the difficulty in observing material within the glare of a star, less than a dozen have been studied closely.

HD 15115 and HIP 12545 are among nearly 30 stars that belong to the Beta Pictoris Moving Group. Moving groups are expanded clusters of stars believed to have a common birthplace and age that are traveling loosely together through space.

The dusty disk around HD 15115 was first inferred by observations at infrared wavelengths in 2000 and its existence confirmed in 2006 when the Hubble Space Telescope (HST) resolved the disk in reflected light for the first time. The disk was investigated further using Keck adaptive optics in 2006 and 2007.

"The disk was seen in the HST data, but its appearance was so extraordinary we could not be certain that it was real. It took follow-up observations at Keck to confirm that it was a real disk," Kalas said

Astronomers Find Highly Elliptical Disk Around Young Star Hubble Press Release
Close Stellar Encounter? feedback from Dr Kalas @ Centauri Dreams


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Monday, July 23, 2007

New Interstellar Molecule

Click on Image to enlarge. An electron attaches itself to the C8H molecule, freeing a burst of radiation (overall glow seen around the molecule) and leaving the negatively-charged ion C8H-. Credit: Bill Saxton, NRAO/AUI/NSF

Astronomers using data from the Green Bank Telescope (GBT) have found the largest negatively-charged molecule yet seen in space. The discovery of the third negatively-charged molecule, called an anion, in less than a year and the size of the latest anion will force a drastic revision of theoretical models of interstellar chemistry.

A team of scientists from the Harvard-Smithsonian Center for Astrophysics (CfA) found negatively-charged octatetraynyl in a cold, dark cloud of molecular gas. A second team headed by Remijan found octatetraynyl in the envelope of gas around an old, evolved star. In both cases the molecule, a chain of eight carbon atoms and one hydrogen atom, had an extra electron, giving it a negative charge.
[+/-] Click here to expand

About 130 neutral and about a dozen positively-charged molecules have been discovered in space, but the first negatively-charged molecule was not discovered until late last year. The largest previously-discovered negative ion found in space has six carbon atoms and one hydrogen atom.

Ultraviolet light from stars can knock an electron off a molecule, creating a positively-charged ion. Astronomers had thought that molecules would not be able to retain an extra electron, and thus a negative charge, in interstellar space for a significant time. “That obviously is not the case,” said Mike McCarthy of the CfA. “Anions are surprisingly abundant in these regions.”

Until recently, many theoretical models of how chemical reactions evolve in interstellar space have largely neglected the presence of anions. This can no longer be the case, and this means that there are many more ways to build large organic molecules in cosmic environments than have been explored.

Remijan and his colleagues found the octatetraynyl anions in the envelope of the evolved giant star IRC +10 216, about 550 light-years from Earth in the constellation Leo. They found radio waves emitted at specific frequencies characteristic of the charged molecule by searching archival data from the GBT, the largest fully-steerable radio telescope in the world.

Another team from the Harvard-Smithsonian Center for Astrophysics found the same characteristic emission when they observed a cold cloud of molecular gas called TMC-1 in the constellation Taurus. These observations also were done with the GBT. In both cases, preceding laboratory experiments by the CfA team showed which radio frequencies actually are emitted by the molecule, and thus told the astronomers what to look for.

It is essential that likely interstellar molecule candidates are first studied in laboratory experiments so that the radio frequencies they can emit are known in advance of an astronomical observation.

Both teams announced their results in the July 20 edition of the Astrophysical Journal Letters.

Read more: Discovery of New negatively charged Interstellar molecule

MRAO celebrates 50th anniversary
History of MRAO. Apply for a free ticket to Tours & Public Lecture

Saturday, July 21, 2007

M-branes & large X-tra dimensions

Itis courtesy of Barngoddess @ Ramblings from the Reservation

Straight from the horses mouth.

In String Theory, the myriad of particle types is replaced by a single fundamental building block, a `string'. These strings can be closed, like loops, or open, like a hair. As the string moves through time it traces out a tube or a sheet, according to whether it is closed or open. Furthermore, the string is free to vibrate, and different vibrational modes of the string represent the different particle types, since different modes are seen as different masses or spins.

One mode of vibration, or `note', makes the string appear as an electron, another as a photon. There is even a mode describing the graviton, the particle carrying the force of gravity, which is an important reason why String Theory has received so much attention. And gravity is not something we put in by hand. It has to be there in a theory of strings. So, the first great achievement of String Theory was to give a consistent theory of quantum gravity, which resembles GR at macroscopic distances.

In order to describe our world, strings must be extremely tiny objects. So when one studies string theory at low energies, it becomes difficult to see that strings are extended objects — they become effectively zero-dimensional (pointlike). Consequently, the quantum theory describing the low energy limit is a theory that describes the dynamics of these points moving in spacetime, rather than strings. Such theories are called quantum field theories.

However, since string theory also describes gravitational interactions, one expects the low-energy theory to describe particles moving in gravitational backgrounds. Finally, since superstring string theories are supersymmetric, one expects to see supersymmetry appearing in the low-energy approximation. These three facts imply that the low-energy approximation to a superstring theory is a supergravity theory.

Prior to M-theory, strings were thought to be the single fundamental constituent of the universe, according to string theory. When M-theory unified the five superstring theories, another fundamental ingredient was added to the makeup of the universe - membranes.

A membrane, or brane, is a multidimensional object, usually called a p-brane, p referring to the number of dimensions in which it exists.

Joseph Polchinski discovered a fairly obscure feature of string theory. He found that in certain situations the endpoints of strings (strings with "loose ends") would not be able to move with complete freedom as they were attached, or stuck within certain regions of space. Polchinski then reasoned that if the endpoints of open strings are restricted to move within some p-dimensional region of space, then that region of space must be occupied by a p-brane.

Not all strings are confined to p-branes. Strings with closed loops, like the graviton, are completely free to move from membrane to membrane. Of the four force carrier particles, the graviton is unique in this way. Researchers speculate that this is the reason why investigation through the weak force, the strong force, and the electromagnetic force have not hinted at the possibility of extra dimensions. These force carrier particles are strings with endpoints that confine them to their p-branes. Further testing is needed in order to show that extra spatial dimensions indeed exist through experimentation with gravity.

M-theory should be viewed as an 11 dimensional theory that looks 10 dimensional at some points in its space of parameters. Such a theory could have as a fundamental object a Membrane, as opposed to a string. Like a drinking straw seen at a distance, membranes would look like strings when we curl the 11th dimension into a small circle.

Could two 4 dimensional 'universes' have a region in common, like two lines of the same plane have a common point? If so, could something cross from one 'universe' to the other?

The M-Theory vision, although not yet complete, is of the whole observable universe being one of many extended 4 dimensional branes in an 11 dimensional spacetime.
M-Theory Cambridge DAMPT University of Cambridge
The Elegant Universe with Brian Greene @ Nova Physics
Braneworld and the hierarchy in RS1 (Randall-Sundrum 1 Model) by Flip Tomato

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Friday, July 20, 2007

ESA's Earth Explorer Mission

Getting the low down on gravity

The Gravity field and steady-state Ocean Circulation Explorer GOCE mission, due to be launched in spring 2008, is ESA's first satellite dedicated to measuring the Earth’s gravity – a fundamental force of nature that influences many dynamic processes within the Earth’s interior, and on and above its surface.

By measuring the Earth's gravity field and modelling the geoid, or hypothetical surface of the Earth, with extremely high accuracy and spatial resolution, GOCE will significantly advance our knowledge of how the Earth works in several domains – oceanography, geophysics and geodesy – as well as providing insight into the physics and dynamics of the Earth's interior, such as volcanism and earthquakes.

Because the gravitational signal is stronger closer to the Earth, GOCE has been designed to fly in a particularly low orbit - at an altitude of just 250 km. However, the remaining atmosphere at low altitudes creates a demanding environment for the satellite and presented a challenge for its design.

Unlike other missions where various independent instruments are carried aboard the spacecraft, GOCE is unique in that the instrumentation actually forms part of the structure of the satellite. A completely stable, rigid and unchanging local environment is required to acquire extremely high fidelity ‘true’ gravity readings, so the spacecraft intentionally has no mechanical moving parts.

Animation & more @ ESA’s Earth Explorer gravity satellite on show
Image Credits: ESA – AOES Medialab
Phenomenological Quantum Gravity by Bee @ Backreaction
Phenomenology of Quantum Gravity by Lubos @ The Reference Frame

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Wednesday, July 18, 2007

The Bullet Cluster

Composite image of the Bullet Cluster.

When individual galaxies collide and spiral into one another, they discard trails of hot gas that stretch across space, providing signposts to the mayhem. Recognising the signs of collisions between whole clusters of galaxies, however, is not as easy.

The orbiting X-ray telescopes XXM-Newton and Chandra have caught a pair of galaxy clusters merging into a giant cluster. The discovery adds to existing evidence that galaxy clusters can collide faster than previously thought.

During the collision the hot gas (shown in pink) in each cluster is slowed and distorted by a drag force, similar to air resistance. A bullet-shaped cloud of gas forms in one of the clusters.

The optical image from the Magellan and the Hubble Space Telescope shows galaxies in orange and white in the background. Hot gas, which contains the bulk of the normal matter in the cluster, is shown by the Chandra X-ray image, which shows the hot intracluster gas in pink. Gravitational lensing and the distortion of background images by mass in the cluster, reveals the mass of the cluster may be dominated by dark matter (blue), an exotic form of matter abundant in the Universe, with very different properties compared to normal matter.

Major cluster-cluster collisions are expected to be rare, with estimates of their frequency ranging from less than one in a thousand clusters to one in a hundred. On collision, their internal gas is thrown out of equilibrium and if unrecognised, causes underestimation of its mass by between 5 and 20 percent.

This is important because the masses of the various galaxy clusters are used to estimate the cosmological parameters that describe how the Universe expands. So, identifying colliding systems is extremely important to our understanding of the Universe.

X-ray satellites discover the biggest collisions in the Universe from ESA
Image Credits: X-ray: NASA/CXC/CfA/M.Markevitch, Optical and lensing map: NASA/STScI, Magellan/U.Arizona/D.Clowe, Lensing map: ESO WFI

Biggest Collisions in the Universe from Universe Today
A Close Stellar Encounter? debris disk around HD 15115 from Centauri Dreams

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Tuesday, July 17, 2007

Diamonds Unlikely in Gas Giants

A new study finds that diamonds probably don't crystallize in atmospheres of planets such as Uranus and Neptune. The conclusion is contrary to recent speculation that small diamonds would spontaneously form in carbon rich layers of the gas giant planets. White dwarf stars, according to the study, are veritable diamond factories.

Physicists at the Universiteit van Amsterdam and the FOM Institute for Atomic and Molecular Physics in the Netherlands performed a numerical analysis showing that at the temperatures and pressures in gas giant planets like Uranus, arrangements of carbon atoms would be much more suitable for creating tiny bits of graphite rather than diamond.

Although diamond formation in the atmospheres of gas giants is not strictly impossible, the Dutch physicists say that the odds are exceedingly slim that a diamond could have formed under the conditions that exist in Uranus in the entire lifetime of the universe.

In white dwarfs, on the other hand, the simulation shows that the conditions would cause the carbon atoms to line up in configurations that are much more amenable for diamond crystallization.

The conclusion is consistent with the 2004 discovery of a cooling white dwarf star that appears to have a solid diamond core 4000 kilometers across.
Ok, so now you all know what I'm looking for out there
A White Star with sparkling diamond heart radiating bright Light

Monday, July 16, 2007

The Lagoon Nebula

The Lagoon Nebula. Credit & Copyright: Antonio Fernandez

One of the most beautiful photographs of the night sky - Stars battling gas and dust in the Lagoon Nebula.

This photogenic nebula also known as M8 is visible even without binoculars towards the constellation of Sagittarius. The energetic processes of star formation create not only the colors but the chaos.

The red-glowing gas results from high-energy starlight striking interstellar hydrogen gas. The dark dust filaments that lace M8 were created in the atmospheres of cool giant stars and in the debris from supernovae explosions.

The light from M8 we see today left about 5,000 years ago. Light takes about 50 years to cross this section of M8.

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Saturday, July 14, 2007

Star with Mystery Partner?

When stars are more massive than about 8 times the Sun, they end their lives in a spectacular explosion called a supernova.

The outer layers of the star are hurtled out into space at thousands of miles an hour, leaving a debris field of gas and dust. Where the star once was located, a small, incredibly dense object called a neutron star is often found. While only 10 miles or so across, the tightly packed neutrons in such a star contain more mass than the entire Sun.
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A new X-ray image shows the 2,000 year-old-remnant of such a cosmic explosion, known as RCW 103, which occurred about 10,000 light years from Earth. In Chandra's image, the colours of red, green, and blue are mapped to low, medium, and high-energy X-rays. At the center, the bright blue dot is likely the neutron star that astronomers believe formed when the star exploded.

For several years astronomers have struggled to understand the behaviour of this object, which exhibits unusually large variations in its X-ray emission over a period of years. New evidence from Chandra implies that the neutron star near the center is rotating once every 6.7 hours, confirming recent work from XMM-Newton. This is much slower than a neutron star of its age should be spinning.

One possible solution to this mystery is that the massive progenitor star to RCW 103 may not have exploded in isolation. Rather, a low-mass star that is too dim to see directly may be orbiting around the neutron star. Gas flowing from the unseen neighbour onto the neutron star might be powering its X-ray emission, and the interaction of the magnetic field of the two stars could have caused the neutron star to slow its rotation.

RCW 103: A Star with a Mystery Partner?
Credit: NASA/CXC/Penn State/G.Garmire et al

Neutron Star
For a sufficiently massive star, an iron core is formed and still the gravitational collapse has enough energy to heat it up to a high enough temperature to either fuse or fission iron. Either in the aftermath of a supernova or in just a collapsing massive star, the energy gets high enough to break down the iron into alpha particles and other smaller units, and still the pressure continues to build.

When it reaches the threshold of energy necessary to force the combining of electrons and protons to form neutrons, the electron degeneracy limit has been passed and the collapse continues until it is stopped by neutron degeneracy. At this point it appears that the collapse will stop for stars with mass less than two or three solar masses, and the resulting collection of neutrons is called a neutron star. Pulsars are thought to be neutron stars.

If the mass exceeds about three solar masses, then even neutron degeneracy will not stop the collapse, and the core shrinks toward the black hole condition.

This neutron degeneracy radius is about 20 km for a solar mass, compared to about earth size for a solar mass white dwarf. The density is quoted as about a billion tons per teaspoonful compared to 5 tons per teaspoonful for the white dwarf.

Neutron stars may be crystalline with crusts on the order of 100 meters thick and an atmosphere a few centimeters thick. They may have 10 to the 11 times the earth's gravity and a powerful magnetic field. A neutron star might have an atmosphere a few centimeters thick and mountain ranges poking up a few centimeters through the atmosphere. A neutron star is thought to be about 1/100,000 the diameter of the Sun, and a nucleus is on the order of 100,000 times smaller than an atom.

First Light from The Canarias Telescope by Stefan @ BackReaction
Supernova theory strengthened by new observations - ESO release

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Thursday, July 12, 2007

The Galactic Plane in infrared

Click on Image to Enlarge

The emission of the cold dust and gas is invisible to us when observed in normal light, however, this material instead emits at longer wavelength infrared light. Thus, observations of the sky in infrared light can tell us where and how this invisible gas and dust are distributed across the Galaxy. In the regions where stars are actively being formed, the dust is warmed up by the stellar light and also emits in infrared light. Therefore, by tracing this infrared emission we can search for and study the site of current active star formation in our Galaxy.

The stars that we see in the visible images of our Galaxy represent only a fraction of the total material of our Milky Way. In addition there are copious amounts of cold gas and dust existing at temperatures below -200 C. The distribution of this cold gas and dust is not uniform. High density regions gravitationally attract more and more matter from the surrounding regions, until eventually stars are formed.

More stunning images of the Orion Region, Cignus-X Region, and the Large Magellanic Cloud from Akari Results July 2007
Planetary Debris and its effects from Centauri Dreams
Star Surface Polluted by Planetary Debris ESO Science Release
Astronomers Get Better View Of Density Waves In Galaxies @ Science Daily

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Wednesday, July 11, 2007

LISA - Beyond Einstein

The Beyond Einstein Program consists of five proposed missions:

two major observatories and three smaller probes. Technology development already is under way on the proposed observatories. The Laser Interferometer Space Antenna (LISA) would orbit the sun and measure gravitational waves in our galaxy and beyond.

Constellation-X would peer at matter falling into supermassive black holes. The planned probes would investigate the nature of dark energy, the physics of the Big Bang, and the distribution and types of black holes in the universe.

LISA is one project under study by the Einstein Probes Office. To study gravitational waves, LISA would “float” over them, much like a buoy on choppy seas. Image credit: NASA

Original Source: NASA will study Strange Cosmic Phenomena
Einstein's Theory of General Relativity ~podcast~ from Universe Today
Spitzer Finds Water Vapour on Hot, Alien Planet press release 11/07/07
NASA's Stardust & Deep Impact to Observe More Comets And Extrasolar Planets

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Monday, July 09, 2007

ALICE gets uk brain

As construction of the World`s largest machine, the Large Hadron Collider (LHC) at CERN in Geneva (Switzerland), gears up for completion next year, the four main experiments, that will study different aspects of the resulting high-energy particle collisions, are also gearing up. For one such experiment, called ALICE, this process got a step closer last week when a crucial part of the 10,000-ton detector, the British-built Central Trigger Processor (CTP), was installed in the ALICE cavern, some 150 feet underground.

The ALICE experiment will probe the mysteries surrounding the structure of matter. Head-on collisions of lead nuclei at the LHC will create sub-atomic sized fireballs with huge temperatures and densities and recreate the conditions that are believed to have existed less than a millionth of a second after an event commonly known as the Big Bang.

These 'mini Big Bangs' will produce temperatures of over a trillion degrees - 100,000 times hotter than the centre of the Sun – and neutrons and protons (which make up the nuclei of atoms) are expected to 'melt' into a new state of matter – quark-gluon plasma.

A quark-gluon plasma (QGP) is a phase of quantum chromodynamics (QCD) which exists at extremely high temperature and/or density. This phase consists of (almost) free quarks and gluons which are the basic building blocks of matter. QGP is believed to have existed during the first 20 to 30 microseconds after the universe came into existence in the process following a Big Bang.

Contrary to popular myth, ALICE is not likely to produce Black Holes, nor the singularities produced by matter in bulk.

ALICE, is the acronym for A Large Ion Collider Experiment, one of the largest experiments in the world devoted to research in the physics of matter at an infinitely small scale.

Scientists have found that everything in the Universe is made up from a small number of basic building blocks called elementary particles, governed by a few fundamental forces.

Some of these particles are stable and form the normal matter, the others live for fractions of a second and then decay to the stable ones. All of them would have coexisted for a few instants after the Big Bang.

Since then, only the enormous concentration of energy that can be reached in an accelerator at CERN can bring them back to life. Therefore, studying particle collisions is like "looking back in time", recreating the environment present at the origin of our Universe.

By studying particle collisions we hope to learn more about the force that holds atomic nuclei together (the strong force), the origin of the mass of nuclear matter and much, much more.

The most familiar basic force is gravity. It keeps our feet on the ground and the planets in motion around the Sun. On individual particles though, the effects of gravity are extremely small. Only when we have matter in bulk - as in ourselves or in planets - does gravity dominate.
Microscopic microstate blackholes at the LHC by Lubos @ the Reference Frame
The Quark Gluon Plasma paradox by Dorigo @ A Quantum Diaries Survivor
NASA scientists pioneer technique for 'weighing' black holes EurekAlert!

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Saturday, July 07, 2007

Jumping Horse

Horse jumping by customcabv6

No matter how dark and grey
it may have been yesterday
the hot sun comes out to play

with its bright gold sunray

Tired from the previous day
Go wash the tiredness away
don't miss a single moment
of this glorious sunny day

The joy of living the joy of it all. No matter how we stumble or how bad the fall, there's always something to bring joy to the thrill of it all. Darn, sometimes it's good simply to be alive to the thrill of it all.

There are things we cannot change and there are things we can. The measure of the man or the measure of our life is what we do with it, not what we could have done or what we did not do, but what we DO.
Hope you all get to catch a glimpse of Live Earth - Enjoy!

Friday, July 06, 2007

Cosmic Blackholes

By including black holes for the first time in a large-scale cosmological simulation, physicists uncover their function in regulating the growth of galaxies

Fixing Blackholes by Tiziana di Matteo
Most Detailed Cosmoligal Simulation to Date from Carnegie Mellon
Evolution of structure from Universe Today
Predicting where to aim future telescopes from Sciene Daily
Europe Plays Lead Role In New Age Of Astronomical Discovery

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Wednesday, July 04, 2007

Stellar Fireworks

Nearly 12.5 million light-years away, in the dwarf galaxy NGC 4449, stellar fireworks on display have been captured by the Hubble Space Telescope. NGC 4449 belongs to a group of galaxies in the constellation Canes Venatici, ‘the Hunting Dogs’. Astronomers think that NGC 4449’s episode of star formation has been influenced by interactions with several of its neighbours. It is likely that the current widespread starburst was triggered by interaction or merger with a smaller companion.

The NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys observed NGC 4449 in the visible (blue and green), infrared, and hydrogen-alpha regions of the spectrum.

Hundreds of thousands of vibrant blue and red stars are visible in this new image. Hot bluish white clusters of massive stars are scattered throughout the galaxy, interspersed with numerous dustier reddish regions where star formation is taking place. Massive, dark clouds of gas and dust are silhouetted against starlight.

NGC 4449 has been forming stars for thousands of millions of years, but is currently experiencing star formation at a much higher rate than in the past. This unusual explosive and intense activity qualifies as a starburst, meaning that at the current rate, the gas that feeds stellar production would run out in about a thousand million years.

Starbursts usually occur in the central regions of galaxies, but in NGC 4449 it is more widespread, since the youngest stars are present both in the nucleus and in streams surrounding the galaxy.

A galaxy-wide starburst such as that seen in NGC 4449 resembles primordial star-forming galaxies, which grew by merging with and accreting smaller stellar systems. Since it is close enough to be observed in detail, NGC 4449 is the ideal laboratory for the investigation of what may have occurred during galactic formation and evolution in the early Universe.

Stellar Fireworks Are Ablaze in Galaxy NGC 4449 A Hubble Heritage Release
Stellar fireworks through Hubble’s eyes plusanimation - from ESA

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Tuesday, July 03, 2007

The Big Bounce

What Happened Before The Big Bang?
Gazing Ball by qwerty

The idea that the universe erupted with a Big Bang explosion has been a big barrier in scientific attempts to understand the origin of our expanding universe, although the Big Bang long has been considered by physicists to be the best model. As described by Einstein's Theory of General Relativity, the origin of the Big Bang is a mathematically nonsensical state -- a "singularity" of zero volume that nevertheless contained infinite density and infinitely large energy.

Physicists at Penn State are exploring territory unknown even to Einstein -- the time before the Big Bang -- using a mathematical time machine called Loop Quantum Gravity. This theory, which combines Einstein's Theory of General Relativity with equations of quantum physics that did not exist in Einstein's day, is the first mathematical description to systematically establish the existence of the Big Bounce and to deduce properties of the earlier universe from which our own may have sprung. For scientists, the Big Bounce opens a crack in the barrier that was the Big Bang.
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"Einstein's Theory of General Relativity does not include the quantum physics that you must have in order to describe the extremely high energies that dominated our universe during its very early evolution," Martin Bojowald, assistant professor of physics at Penn State explained, "but we now have Loop Quantum Gravity, a theory that does include the necessary quantum physics."

Loop Quantum Gravity was pioneered and is being developed in the Penn State Institute for Gravitational Physics and Geometry, and is now a leading approach to the goal of unifying general relativity with quantum physics. Scientists using this theory to trace our universe backward in time have found that its beginning point had a minimum volume that is not zero and a maximum energy that is not infinite. As a result of these limits, the theory's equations continue to produce valid mathematical results past the point of the classical Big Bang, giving scientists a window into the time before the Big Bounce.

Quantum-gravity theory indicates that the fabric of space-time has an "atomic" geometry that is woven with one-dimensional quantum threads. This fabric tears violently under the extreme conditions dominated by quantum physics near the Big Bounce, causing gravity to become strongly repulsive so that, instead of vanishing into infinity as predicted by Einstein's Theory of General Relativity, the universe rebounded in the Big Bounce that gave birth to our expanding universe. The theory reveals a contracting universe before the Big Bounce, with space-time geometry that otherwise was similar to that of our universe today.

Bojowald found he had to create a new mathematical model to use with the theory of Loop Quantum Gravity in order to explore the universe before the Big Bounce with more precision. "A more precise model was needed within Loop Quantum Gravity than the existing numerical methods, which require successive approximations of the solutions and yield results that are not as general and complete as one would like," Bojowald explained. He developed a mathematical model that produces precise analytical solutions by solving of a set of mathematical equations.

In addition to being more precise, Bojowald's new model also is much shorter. He reformulated the quantum-gravity models using a different mathematical description, which he says made it possible to solve the equations explicitly and also turned out to be a strong simplification. "The earlier numerical model looked much more complicated, but its solutions looked very clean, which was a clue that such a mathematical simplification might exist," he said. Bojowald reformulated quantum gravity's differential equations -- which require many calculations of numerous consecutive small changes in time -- into an integrable system -- in which a cumulative length of time can be specified for adding up all the small incremental changes.

The model's equations require parameters that describe the state of our current universe accurately so that scientists then can use the model to travel backward in time, mathematically "un-evolving" the universe to reveal its state at earlier times. The model's equations also contain some "free" parameters that are not yet known precisely but are nevertheless necessary to describe certain properties. Bojowald discovered that two of these free parameters are complementary: one is relevant almost exclusively after the Big Bounce and the other is relevant almost exclusively before the Big Bounce. Because one of these free parameters has essentially no influence on calculations of our current universe, Bojowald colludes that it cannot be used as a tool for back-calculating its value in the earlier universe before the Big Bounce.

The two free parameters, which Bojowald found were complementary, represent the quantum uncertainty in the total volume of the universe before and after the Big Bang. "These uncertainties are additional parameters that apply when you put a system into a quantum context such as a theory of quantum gravity," Bojowald said. "It is similar to the uncertainty relations in quantum physics, where there is complimentarity between the position of an object and its velocity -- if you measure one you cannot simultaneously measure the other."

Similarly, Bojowald's study indicates that there is complementarity between the uncertainty factors for the volume of the universe before the Big Bounce and the universe after the Big Bounce. "For all practical purposes, the precise uncertainty factor for the volume of the previous universe never will be determined by a procedure of calculating backwards from conditions in our present universe, even with most accurate measurements we ever will be able to make," Bojowald explained. This discovery implies further limitations for discovering whether the matter in the universe before the Big Bang was dominated more strongly by quantum or classical properties.

"A problem with the earlier numerical model is you don't see so clearly what the free parameters really are and what their influence is," Bojowald said. "This mathematical model gives you an improved expression that contains all the free parameters and you can immediately see the influence of each one," he explained. "After the equations were solved, it was rather immediate to reach conclusions from the results."

Bojowald reached an additional conclusion after finding that at least one of the parameters of the previous universe did not survive its trip through the Big Bounce -- that successive universes likely will not be perfect replicas of each other. He said, "the eternal recurrence of absolutely identical universes would seem to be prevented by the apparent existence of an intrinsic cosmic forgetfulness."

The Planck Scale from Bee @ Backreaction
Before the big bang from Universe Today
Against Bounces counterargument from Sean @ Cosmic Variance

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Monday, July 02, 2007

Invisible nano-fibres

New Invisible Nano-fibers Conduct Electricity, Repel Dirt

A drop of water balances perfectly on a plastic surface invented by researchers at Ohio State University. The surface is covered with microscopic fibers, and can be made to attract or repel water. The surface shown here is water repellant, so the drop can't spread out along the surface; instead, it retains its spherical shape. (Credit: Photo by Jo McCulty, courtesy of Ohio State University)
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They devised one treatment that made the fibers attract water, and another that made the fibers repel water. They found they could also make the surfaces attract or repel oil. Depending on what polymer they start with, the fibers can also be made to conduct electricity.

The ability to tailor the properties of the fibers opens the surface to many different applications.
Since dirt, water, and oil don't stick to the repellant fibers, windows coated with them would stay cleaner longer. In contrast, the attracting fibers would make a good anti-fog coating, because they pull at water droplets and cause them to spread out flat on the surface.

What's more, researchers found that the attracting surface does the same thing to coiled-up strands of DNA. When they put droplets of water containing DNA on the fibers, the strands uncoiled and hung suspended from the fibers like clotheslines.

The patent-pending technology involves a method for growing a bed of fibers of a specific length, and using chemical treatments to tailor the fibers' properties, explained Arthur J. Epstein, University Professor of chemistry and physics and director of the university's Institute for Magnetic and Electronic Polymers.

Epstein's research centers on polymers that conduct electricity, and light up or change color. Depending on the choice of polymer, the nano-fiber surface can also conduct electricity. The researchers were able to use the surface to charge an organic light-emitting device -- a find that could pave the way for transparent plastic electronics. Finally, they also showed that the fibers could be used to control the flow of water in microfluidic devices.

The technology is a merger of two different chemical processes for growing polymer molecules: one grows tiny dots of polymer "seeds" on a flat surface, and the other grows vertical fibers out from the top of the seeds. The fibers grow until the scientists cut off the chemical reaction, forming a carpet of uniform height. The university will license the technology, and Epstein and his colleagues are looking for new applications for it.

Original Source: Ohio State University

Spider and water bubbles courtesy of Annelisa @ Words that flow