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(Astronomy) Universe: Supernovas Shed Light on Dark Energy
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PostPosted: Mon Jan 09, 2006 11:29 am    Post subject: (Astronomy) Universe: Supernovas Shed Light on Dark Energy Reply with quote






Supernovas Shed Light on Dark Energy

Emily Sohn

It's mysterious. It's so dark that it's invisible. And, boy, is it repulsive! Still, astronomers who study dark energy in the universe keep learning new things about it.

Scientists came up with the bizarre concept of dark energy 8 years ago to explain mysterious data that they were collecting from outer space. The data appeared to show that, about 6 billion years ago, something began pushing everything in the universe farther and farther apart at an ever-faster rate.

Scientists called this something "dark energy" and suggested that it supplies a repulsive force that causes the universe to expand outward with increasing speed. Most experts now agree that dark energy exists, but they still have a lot to learn about it.

To find out more, an international team looked at images taken by the Canada-France-Hawaii Telescope on top of Hawaii's Mauna Kea. The astronomers identified 71 supernovas of a certain type known as "1a." These are very old stars that explode when they die. We see the light that they emit a few billion years later.

Looking at type 1a supernovas is a good way to learn about the expansion of the universe because the explosions are all roughly equal in brightness at the source, just as all 100-watt light bulbs are equally bright. The farther away they are, though, the dimmer they look. So scientists can look at the brightness of supernovas and figure out how far away they are from Earth.

Also, each supernova gives off a spectrum, or combination of wavelengths, of light. This spectrum shows how quickly the star's galaxy was moving away when the star exploded.

Using all of this information, the researchers were able to figure out how long ago each of the 71 supernovas exploded. They were also able to estimate the speed of expansion at different times in the history of the universe.

Their analyses suggest that dark energy is spread equally throughout space and time, the scientists say. The findings also help validate what Albert Einstein called a "cosmological constant." The famous scientist came up with the idea when he proposed a theory of gravitation in 1917, but he quickly retracted the part about the cosmological constant. It just seemed too weird at the time.

Weird, but true. Astronomers plan to continue studying supernovas that exploded at various times. The more they do, the closer they'll get to understanding what dark energy is all about.—E. Sohn


http://www.sciencenewsforkids....../Note3.asp

From Science News for Kids Dec. 21, 2005.

*************************************************************

Questions to explore further this topic:

What is the universe?

Flat earth universe
http://www.pbs.org/wnet/hawkin...../flat.html

Ptolemy's universe
http://www.pbs.org/wnet/hawkin.....ptole.html

Copernicus' universe
http://www.pbs.org/wnet/hawkin.....coper.html

Kepler's universe
http://www.pbs.org/wnet/hawkin.....epler.html

Steady-state universe
http://www.pbs.org/wnet/hawkin.....teady.html

Big Bang universe
http://www.pbs.org/wnet/hawkin...../bang.html

Friedmann universe
http://www.pbs.org/wnet/hawkin.....fried.html

Anthropic universe
http://www.pbs.org/wnet/hawkin...../anth.html

Inflationary universe
http://www.pbs.org/wnet/hawkin.....infla.html

No-boundary universe
http://www.pbs.org/wnet/hawkin.....bound.html

Oscillating universe
http://www.pbs.org/wnet/hawkin...../osci.html

Where does matter come from?

http://www.pbs.org/wnet/hawkin.....ser-1.html

The history of the universe

http://www.pbs.org/deepspace/timeline/index.html
http://www.historyoftheuniverse.com/index.html
http://www.damtp.cam.ac.uk/use....._home.html

What are galaxies?

http://csep10.phys.utk.edu/ast.....axies.html

Types of galaxies

http://www.damtp.cam.ac.uk/use.....class.html
http://www.smv.org/hastings/galaxy.htm

Galaxy clusters

http://www.damtp.cam.ac.uk/use.....l_lss.html

The Andromeda Galaxy

http://www.solstation.com/x-objects/andromeda.htm

The Milky Way (Our galaxy)

http://www.damtp.cam.ac.uk/use.....milky.html
http://www.seds.org/messier/more/mw.html
http://home.cwru.edu/~sjr16/index.html
http://cassfos02.ucsd.edu/public/tutorial/MW.html
http://csep10.phys.utk.edu/ast.....nents.html

A tour of galaxies

http://school.discovery.com/sc.....index.html

What is a supernova?

http://heasarc.gsfc.nasa.gov/docs/snr.html
http://imagine.gsfc.nasa.gov/d.....novae.html
http://hyperphysics.phy-astr.g.....novcn.html

What is dark energy?

http://www.space.com/scienceas.....115-1.html

GAMES

http://amazing-space.stsci.edu.....es-galore/


Last edited by adedios on Sat Jan 27, 2007 5:01 pm; edited 2 times in total
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PostPosted: Fri Mar 17, 2006 6:55 am    Post subject: New satellite data on universe's first trillionth second Reply with quote

Johns Hopkins University
16 March 2006


New satellite data on universe's first trillionth second

Scientists peering back to the oldest light in the universe have new evidence for what happened within its first trillionth of a second, when the universe suddenly grew from submicroscopic to astronomical size in far less than a wink of the eye.

Using new data from a NASA satellite, scientists have the best evidence yet to support this scenario, known as "inflation." The evidence, from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, was gathered during three years of continuous observations of remnant afterglow light -- cosmic background radiation that lingers, much cooled, from the universe's energetic beginnings 13.7 billion years ago.

In 2003, NASA announced that the WMAP satellite had produced a detailed picture of the infant universe by measuring fluctuations in temperature of the afterglow -- answering many longstanding questions about the universe's age, composition and development. The WMAP team has built upon those results with a new measurement of the faint glare from the afterglow to obtain clues about the universe's first moments, when the seeds were sown for the formation of the first stars 400 million years later.

"It amazes me that we can say anything about what transpired within the first trillionth of a second of the universe, but we can," said Charles L. Bennett, WMAP principal investigator and a professor in the Henry A. Rowland Department of Physics and Astronomy at The Johns Hopkins University. "We have never before been able to understand the infant universe with such precision. It appears that the infant universe had the kind of growth spurt that would alarm any mom or dad."

WMAP results have been submitted to the Astrophysical Journal and are posted online at http://wmap.gsfc.nasa.gov/results.

The newly detected pattern, or polarization signal, in the glare of the afterglow is the weakest cosmological signal ever detected -- less than a hundredth of the strength of the temperature signal reported three years ago.

"This is brand new territory," said Princeton University physicist Lyman Page, a WMAP team member. "We are quantifying the cosmos in a different way to open up a new window for understanding the universe in its earliest times."

Comparing the brightness of broad features to compact features in the afterglow light (like comparing the heights of short-distance ripples versus long-distance waves on a lake) helps tell the story of the infant universe. One long-held prediction was that the brightness would be the same for features of all sizes. In contrast, the simplest versions of inflation predict that the relative brightness decreases as the features get smaller. WMAP data are new evidence for the inflation prediction.

The new WMAP data, combined with other cosmology data, also support established theories on what has happened to matter and energy over the past 13.7 billion years since its inflation, according to the WMAP researchers. The result is a tightly constrained and consistent picture of how our universe grew from microscopic quantum fluctuations to enable the formation of stars, planets and life.

According to this picture, researchers say, only 4 percent of the universe is ordinary familiar atoms; another 22 percent is an as-yet unidentified dark matter, and 74 percent is a mysterious dark energy. That dark energy is now causing another growth spurt for the universe, fortunately, they say, more gentle than the one 13.7 billion years ago.

WMAP was launched on June 30, 2001, and is now a million miles from Earth in the direction opposite the sun. It is able to track temperature fluctuations at levels finer than a millionth of a degree.


###
The WMAP team includes researchers at the Goddard Space Flight Center in Greenbelt, Md.; The Johns Hopkins University; Princeton University; the Canadian Institute of Theoretical Astrophysics in Toronto; the University of Texas at Austin; Cornell University; the University of Chicago; Brown University; the University of British Columbia; the University of Pennsylvania; and the University of California, Los Angeles.

For images and more information: http://wmap.gsfc.nasa.gov/results
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PostPosted: Mon May 08, 2006 8:00 pm    Post subject: Recycled Universe: Theory Could Solve Cosmic Mystery Reply with quote

Recycled Universe: Theory Could Solve Cosmic Mystery
By Ker Than
Staff Writer
posted: 08 May 2006
12:28 am ET
http://www.space.com/scienceas.....verse.html

One of the biggest mysteries in cosmology could be explained by a controversial theory in which the universe explodes into existence not just once, but repeatedly in endless cycles of death and rebirth.

Called the cyclic universe theory, it could potentially explain why a mysterious repulsive form of energy known as the "cosmological constant" and which is accelerating the expansion of the universe is several orders of magnitude smaller than predicted by the standard Big Bang model.

In a new study detailed in the May 5 issue of the journal Science, Paul Steinhardt of Princeton University and Neil Turok of Cambridge University propose that the constant was once much larger, but that its value decayed with each incarnation of the universe.

Puzzling great minds

The cosmological constant, also known as "lambda", is thought to be a form of energy that gravitationally repels itself and causes the expansion of the universe to speed up.

Einstein initially proposed it as a counterforce to the gravitational attraction of matter to explain why the universe appeared static, neither growing nor shrinking. He later discarded the idea, however, when observations by astronomer Edwin Hubble revealed the universe was in fact expanding.

Lambda was revived in the late 1990s when astronomers discovered that the universe was not only expanding, but that it was doing so at an accelerated pace.

Scientists are still not sure what lambda is. According to one popular idea, it is the energy of space itself. According to quantum physics, the seemingly empty vacuum of space actually contains phantom particles that continually blink in and out of existence like flecks of sea foam. These particles are fleeting, but their energies combine to give every cubic centimeter of space a certain amount of energy. According to general relativity, this "vacuum energy" produces an anti-gravitational force that pushes space—and the matter in it—apart.

But there is a problem: the lambda that scientists have detected is more than a googol (1 followed by 100 zeros)times smaller than what theory predicts. To explain such a large discrepancy, physicists have been forced to come up with ever wilder theories.

Explaining lambda

One idea is that the lambda is not really small, but only seems so because it is being cancelled out by another unknown force with near perfect precision. To date, though, no mechanism has been found that can cause this cancellation.

An alternative solution is that of "anthropic selection," a controversial idea that attempts to explain why so many constants in nature appear to be precisely the right value to produce life. If lambda were too large, for example, the universe would have instantly blown up shortly after the Big Bang.

According to the so-called Anthropic Principle, certain features of the universe are selected by the requirement that observers—in our case, humans—can detect them. In other words, only in a universe where lambda is small can intelligent beings exist who can wonder why it is small.

There are different ideas about how anthropic selection works. One possibility is that there are many parallel universes coexisting together; each would have constants of different values and in our universe, those constants can sustain life.

A similar idea is that there is only one infinite universe, but lambda varies from region to region. We just happen to live in a rare bubble where the constant is just right for galaxies and stars—and us—to form.

Anthropic selection makes many scientists uneasy because it suggests that the laws of physics might work differently in remote parts of the universe. In its strongest form, anthropic selection could also be viewed as support for creationism, since it suggests that the universe is somehow fine-tuned specifically for intelligent life.

"The anthropic idea suggests that, in order to explain the universe that we do see, we must make very strong assumptions about other universes we can never see," Steinhardt told SPACE.com. "Also, it assumes our universe is atypical. These assumptions are not normal in science and it's not clear that we must head in such a radical direction."

Cyclic universe

The idea of a cyclic universe, first proposed in 2002 by Steinhardt and Turok, is an alternative to anthropic selection.

"The [value of lambda] is one of the prime mysteries of physics," Steinhardt said. "It's really been so puzzling that it's driven the physics community to this anthropic approach. So it's important to know if a non-anthropic solution might exist."

The researchers' latest tweak to their model is to have the value of lambda decay over time with each passing cycle of the universe and even within a single cycle.

Scientists experimented with a varying lambda before within the context of the standard Big Bang model, but it didn't work because the time required for it to reach its current low value was far longer than the known age of the universe.

Combining a decaying lambda with a cyclic universe potentially solves this problem.

'Ingenious'

Although he expressed other concerns about the cyclic universe theory, Alexander Vilenkin, a cosmologist at Tufts University in Massachusetts who was not involved in the study, said Steinhardt and Turok's solution to the cosmological constant problem was "ingenious."

In a cyclic universe, new matter and energy are created about every trillion years when two sheet-like "branes" collide along an extra dimension of space. Branes are predicted by string theory.

Because there can be endless cycles, the universe would be far older than the 14.7 billion years that scientists currently estimate. This would allow ample time for lambda to shrink to what astronomers see now.

Steinhardt and Turok think lambda decreased in such a way that the rate of decay slowed with time. This means that observers measuring lambda are much more likely to get a small value than a large one.

Because a high lamda prevents the universe as we know it from forming, early cycles of the universe would have been void of galaxies, stars and life; only in later cycles, when lamda had decreased to a much smaller value, could matter coalesce to create the world we inhabit today.

The pair estimates that each cycle lasted about a trillion years. During this time, the universe runs its natural course, but all the while matter and energy fans out through space until they are extremely dilute.

"They are so dilute, in fact, that we would likely see not even a single particle of that early matter and radiation within our horizon—that is, the patch of space we can see," Steinhardt said.

Once the universe is emptied out, a weak attractive force brings our universe's two branes together in a cosmic collision. Each collision is essentially a new Big Bang that infuses the aging universe with new matter and energy.

Steinhardt says their crazy theory can be tested: the inflationary Big Bang theory predicts that gravitational waves produced at the end of inflation leave an imprint on the cosmic microwave background, a diffuse form of electromagnetic radiation that fills the universe.

If future experiments show the polarization pattern produced by such waves, it would disprove the cyclic universe theory, ruling it out as a possible solution to the cosmological constant problem.
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PostPosted: Mon May 15, 2006 6:09 pm    Post subject: A ruler to measure the universe Reply with quote

15-May-2006
Monthly Notices of the Royal Astronomical Society
A ruler to measure the universe

Astronomers with the Sloan Digital Sky Survey, including principal authors now at Lawrence Berkeley National Laboratory, have published the largest three-dimensional map of the universe ever constructed, a wedge-shaped slice of the cosmos that encompasses 600,000 uniquely luminous red galaxies and extends 40 percent of the way back in time to the Big Bang. Large-scale structures repeating every 450 million light years confirm the accelerating expansion of the universe due to dark energy.

The full article:
http://www.lbl.gov/Science-Art.....ruler.html
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PostPosted: Mon Jun 05, 2006 1:59 pm    Post subject: Galaxy evolution in cyber universe Reply with quote

University of Chicago
5 June 2006

Galaxy evolution in cyber universe matches astronomical observations in fine detail

Scientists at the University of Chicago have bolstered the case for a popular scenario of the big bang theory that neatly explains the arrangement of galaxies throughout the universe. Their supercomputer simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe.
Previous studies by other researchers had already verified the main features of this scenario, called the cold dark matter model. The Chicago team further extended this work by comparing the results of their supercomputer simulations to the newest, most detailed astronomical observations available today. They found an excellent fit, and they did so without basing their simulations on a lot of complex assumptions.


"The model we use is really, really simple," said Andrey Kravtsov, Associate Professor in Astronomy & Astrophysics. "We want to see how well this framework can do with a minimum number of assumptions."

A paper co-authored by Kravtsov, Charlie Conroy and Risa Wechsler describing these findings will be published in the June 20 issue of the Astrophysical Journal. The research was funded by a grant from the National Science Foundation, with additional support from the National Aeronautics and Space Administration.

Simulations that Kravtsov's team conducted two years ago had predicted that galaxies of different luminosity or brightness would cluster differently when the universe was young than they do today. The team's Astrophysical Journal paper verifies that prediction and shows that similar differences appear in the recent data.

"In the early stages of evolution of the universe, each galaxy has a high probability of having a close neighbor of similar luminosity," Kravtsov said, much more so than galaxies today. "That was what was predicted and that's what the observations now seem to show us."

The data that Kravtsov's team compared to its simulations came from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey, and from the Sloan Digital Sky Survey.

Using the Keck 10-meter telescopes in Hawaii, DEEP2 took detailed observations of how galaxies were clustered seven billion years ago, when the universe was approximately half its current age. The Sloan Survey, meanwhile, provided additional data regarding galaxy clustering from more recent epochs in the history of the universe.

"We essentially have data on the distribution of galaxies over most of the evolution of the universe, and the data are accurate," Kravtsov said. "Although the measurements at earlier epochs have larger errors, due to smaller data sets, their accuracy and power to constrain theoretical models is quite remarkable."

The Chicago scientists based their supercomputer simulations on the assumption that galaxies form in the center of dark-matter halos.

According to this scheme, gravity causes the dark matter in these regions to collapse into halos. These halos provide a central location where normal matter consisting of hydrogen, helium and a small amount of heavier elements would collect in gaseous form. Once this gas had cooled and condensed, it achieved sufficient density for star formation to begin on a galactic scale.

When the Chicago team compared the distribution of galaxies in its cyber universe to the real one, "that scheme turned out to work extremely well," Kravtsov said. "It wasn't guaranteed that it would actually work so well in reproducing the data."

Some fields of astrophysics are less fortunate: they have a large body of data but no way to explain it. "The data just kind of hang there. Nobody quite understands what it's telling us or how to interpret it."

But the Chicago simulations further support the idea that the universe behaves the way the cold dark matter scenario tells them it should, that galaxies tend to form in high-density regions of dark matter.

"We understand the distribution of these dark-matter halos, and the implication of this analysis is that we also understand how the properties of these halos are related to galaxy luminosity, how bright the galaxy is," Kravtsov said.

Brighter galaxies also are found in more pronounced large-scale structures. "If you look at fainter galaxies, their distribution becomes more diffuse. We can still see structure, but it's not as pronounced."

Additional data continues to become available. For example, the Sloan Survey has gone beyond mapping the galaxies to include measurements of the dark matter that surrounds them. And other new, high-quality data regarding the distribution of galaxies from the very early stages in the evolution of the universe are becoming available. The first comparisons of the theory's predictions with that data indicate good agreement over the span of about 12 billion years, Kravtsov said.
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PostPosted: Mon Jun 12, 2006 12:02 pm    Post subject: Galaxy Evolution In Cyber Universe Reply with quote

Source: University of Chicago

Posted: June 12, 2006


Galaxy Evolution In Cyber Universe Matches Astronomical Observations In Fine Detail

Scientists at the University of Chicago have bolstered the case for a popular scenario of the big bang theory that neatly explains the arrangement of galaxies throughout the universe. Their supercomputer simulation shows how dark matter, an invisible material of unknown composition, herded luminous matter in the universe from its initial smooth state into the cosmic web of galaxies and galaxy clusters that populate the universe.


Previous studies by other researchers had already verified the main features of this scenario, called the cold dark matter model. The Chicago team further extended this work by comparing the results of their supercomputer simulations to the newest, most detailed astronomical observations available today. They found an excellent fit, and they did so without basing their simulations on a lot of complex assumptions.

“The model we use is really, really simple,” said Andrey Kravtsov, Associate Professor in Astronomy & Astrophysics. “We want to see how well this framework can do with a minimum number of assumptions.”

A paper co-authored by Kravtsov, Charlie Conroy and Risa Wechsler describing these findings will be published in the June 20 issue of the Astrophysical Journal. The research was funded by a grant from the National Science Foundation, with additional support from the National Aeronautics and Space Administration.

Simulations that Kravtsov’s team conducted two years ago had predicted that galaxies of different luminosity or brightness would cluster differently when the universe was young than they do today. The team’s Astrophysical Journal paper verifies that prediction and shows that similar differences appear in the recent data.

“In the early stages of evolution of the universe, each galaxy has a high probability of having a close neighbor of similar luminosity,” Kravtsov said, much more so than galaxies today. “That was what was predicted and that’s what the observations now seem to show us.”

The data that Kravtsov’s team compared to its simulations came from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey, and from the Sloan Digital Sky Survey.

Using the Keck 10-meter telescopes in Hawaii, DEEP2 took detailed observations of how galaxies were clustered seven billion years ago, when the universe was approximately half its current age. The Sloan Survey, meanwhile, provided additional data regarding galaxy clustering from more recent epochs in the history of the universe.

“We essentially have data on the distribution of galaxies over most of the evolution of the universe, and the data are accurate,” Kravtsov said. “Although the measurements at earlier epochs have larger errors, due to smaller data sets, their accuracy and power to constrain theoretical models is quite remarkable.”

The Chicago scientists based their supercomputer simulations on the assumption that galaxies form in the center of dark-matter halos.

According to this scheme, gravity causes the dark matter in these regions to collapse into halos. These halos provide a central location where normal matter consisting of hydrogen, helium and a small amount of heavier elements would collect in gaseous form. Once this gas had cooled and condensed, it achieved sufficient density for star formation to begin on a galactic scale.

When the Chicago team compared the distribution of galaxies in its cyber universe to the real one, “that scheme turned out to work extremely well,” Kravtsov said. “It wasn’t guaranteed that it would actually work so well in reproducing the data.”

Some fields of astrophysics are less fortunate: they have a large body of data but no way to explain it. “The data just kind of hang there. Nobody quite understands what it’s telling us or how to interpret it.”

But the Chicago simulations further support the idea that the universe behaves the way the cold dark matter scenario tells them it should, that galaxies tend to form in high-density regions of dark matter.

“We understand the distribution of these dark-matter halos, and the implication of this analysis is that we also understand how the properties of these halos are related to galaxy luminosity, how bright the galaxy is,” Kravtsov said.

Brighter galaxies also are found in more pronounced large-scale structures. “If you look at fainter galaxies, their distribution becomes more diffuse. We can still see structure, but it’s not as pronounced.”

Additional data continues to become available. For example, the Sloan Survey has gone beyond mapping the galaxies to include measurements of the dark matter that surrounds them. And other new, high-quality data regarding the distribution of galaxies from the very early stages in the evolution of the universe are becoming available. The first comparisons of the theory’s predictions with that data indicate good agreement over the span of about 12 billion years, Kravtsov said.
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PostPosted: Fri Aug 04, 2006 7:14 am    Post subject: ASTRONOMERS CRUNCH NUMBERS, UNIVERSE GETS BIGGER Reply with quote

ASTRONOMERS CRUNCH NUMBERS, UNIVERSE GETS BIGGER
August 3, 2006
Ohio State University

COLUMBUS , Ohio – That intergalactic road trip to Triangulum is going to take a little longer than you had planned.

An Ohio State University astronomer and his colleagues have determined that the Triangulum Galaxy, otherwise known as M33, is actually about 15 percent farther away from our galaxy than previously measured.

This finding implies that the Hubble constant, a number that astronomers rely on to calculate a host of factors -- including the size and age of the universe -- could be significantly off the mark as well.

That means that the universe could be 15 percent bigger and 15 percent older than any previous calculations suggested.

For the full article:

http://researchnews.osu.edu/archive/biguni.htm
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PostPosted: Mon Aug 14, 2006 2:53 pm    Post subject: Surprising telescope observations Reply with quote

University of Colorado at Boulder
14 August 2006

Surprising telescope observations shake up galactic formation theories

--------------------------------------------------------------------------------

A heavy form of hydrogen created just moments after the Big Bang has been found to exist in larger quantities than expected in the Milky Way, a finding that could radically alter theories about star and galaxy formation, says a new international study led by the University of Colorado at Boulder.

CU-Boulder astrophysicist Jeffrey Linsky said new data gathered by NASA's Far Ultraviolet Spectroscopic Explorer, or FUSE, satellite, shows why deuterium appears to be distributed unevenly in the Milky Way Galaxy. It apparently has been binding to interstellar dust grains, changing from an easily detectable gaseous form to an unobservable solid form, said Linsky, a fellow of JILA, a joint institute of CU-Boulder and the National Institute of Standards and Technology.

The FUSE deuterium study, six years in the making, solves a 35-year-old mystery concerning the distribution of deuterium in the Milky Way while posing new questions about how stars and galaxies are made, according to the research team. A paper on the subject by a team of international researchers led by Linsky is being published in the Aug. 20 issue of The Astrophysical Journal.

"Since the 1970s, we have been unable to explain why deuterium levels vary all over the place," said Linsky. "The answer we found is as unsettling as it is exciting."

Since deuterium -- a hydrogen isotope containing a proton and a neutron -- is believed burned and lost forever during star formation, scientists think the amount of deuterium present in the universe is "pure" and serves as a tracer for star creation and galaxy building over billions of years, said Linsky. While primordial deuterium in the distant, early universe has been measured at concentrations of about 27 parts per million parts hydrogen atoms, measurements by FUSE and NASA's Copernicus satellite have shown a "patchy" distribution of the element in the Milky Way galaxy, often at far lower levels.

In 2003, Princeton University's Bruce Draine, a co-author on the new study, developed a model showing that deuterium, when compared to hydrogen, might preferentially bind to interstellar dust grains. The observations by FUSE -- which can detect the telltale spectral fingerprints of deuterium in the ultraviolet energy range -- strongly support the theory, according to The Astrophysical Journal paper authors.

"Where there are high concentrations of interstellar dust in the galaxy, we see lower concentrations of deuterium gas with FUSE," said Linsky. "And where there is less interstellar dust, we are measuring higher levels of deuterium gas."

In relatively undisturbed areas of the universe -- like regions around Earth's sun, for example -- deuterium atoms systematically "leave" the gas phase and replace normal hydrogen atoms in dust grains, said Linsky. When a pocket of the universe is disturbed by events like a supernova shock wave or violent activity triggered by nearby hot stars, the dust grains are vaporized, releasing deuterium atoms back into a gas, which has been measured by FUSE, the researchers said.

Scientists assumed from astrophysical theories that at least one-third of the primordial deuterium present in the Milky Way was destroyed over time as it cycled through the stars, said Linsky. But according to the new FUSE findings, the present-day deuterium abundance is less than 15 percent below the primordial values.

"This implies that either significantly less material has been converted to helium and heavier elements in stars or that much more primordial gas has rained down onto the galaxy over its lifetime than had been thought," said Linsky. "In either case, our models of the chemical evolution of the Milky Way will have to be revised significantly to explain this important new result."

Launched in 1999, FUSE is a NASA Explorer mission developed in cooperation with the French and Canadian Space Agencies and by Johns Hopkins University, CU-Boulder and the University of California, Berkeley. CU-Boulder's Center for Astrophysics and Space Astronomy designed and built the mission's $9 million spectrograph, which collects and funnels UV light from the satellite's four telescopes.


###
The paper was co-authored by scientists from Princeton, Johns Hopkins and Northwestern universities, the Space Telescope Science Institute, CU-Boulder, the University of Wisconsin-Madison, the University of Texas-Austin, NASA-Goddard, the Laboratoire d'Astrophysique in Marseille, France, and the Observatoire de Paris-Meudon in Meudon, France. Other CU-Boulder co-authors include JILA's Brian Wood, CASA's Michael Shull and CASA doctoral graduate Seth Redfield.

For more information on the FUSE satellite and the spacecraft's search for deuterium go to http://fuse.pha.jhu.edu/ and http://fuse.pha.jhu.edu/wpb/sci_d2h.html
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PostPosted: Wed Sep 13, 2006 6:58 pm    Post subject: Astronomers trace the evolution of the first galaxies Reply with quote

University of California - Santa Cruz
13 September 2006

Astronomers trace the evolution of the first galaxies in the universe

SANTA CRUZ, CA--A systematic search for the first bright galaxies to form in the early universe has revealed a dramatic jump in the number of such galaxies around 13 billion years ago. These observations of the earliest stages in the evolution of galaxies provide new evidence for the hierarchical theory of galaxy formation--the idea that large galaxies built up over time as smaller galaxies collided and merged.

Astronomers Rychard Bouwens and Garth Illingworth at the University of California, Santa Cruz, used the Hubble Space Telescope to explore the formation of galaxies during the first 900 million years after the Big Bang. They reported their latest findings in the September 14 issue of the journal Nature.

Deep observations in three dark patches of sky--the Hubble Ultra Deep Field and the Great Observatories Origins Deep Survey fields--gathered the faint light emitted 13 billion years ago by stars in primeval galaxies. Only the brightest galaxies could be detected at such great distances.

"These are the deepest infrared and optical data ever taken. We're looking at a very early stage in the buildup of galaxies," said Illingworth, a professor of astronomy and astrophysics at UCSC.

The researchers observed hundreds of bright galaxies at around 900 million years after the Big Bang. But when they looked deeper, about 200 million years earlier in time, they only found one. Relaxing their search criteria a bit turned up a few more candidates, but clearly a lot of changes took place during those 200 million years, Illingworth said.

"The bigger, more luminous galaxies just were not in place at 700 million years after the Big Bang. Yet 200 million years later there were many more of them, so there must have been a lot of merging of smaller galaxies during that time," he said.

Astronomers can determine when light was emitted from a distant source by its redshift, a measure of how the expansion of the universe stretched the wavelengths of the light as it traveled through space across vast distances. Bouwens, a postdoctoral fellow at UCSC and first author of the Nature paper, developed software to systematically sift through the Hubble data in search of high-redshift galaxies.

The data came from two powerful instruments on Hubble, the Advanced Camera for Surveys (ACS) and the Near Infrared Camera and Multi-Object Spectrograph (NICMOS). The researchers compared the numbers of galaxies detected at a redshift of 7 to 8 (700 million years after the Big Bang) with what they might have expected to find if the population of galaxies then were like the population they had observed at redshift 6 (200 million years later). Depending on the strictness of their selection criteria, they found one galaxy where they would have expected 10, or four where they would have expected 17.

"Our approach provides a very quantitative way of measuring the buildup of structure in the universe, so we can see how fast it changed over time as smaller galaxies merged to form larger ones," Bouwens said.

The galaxies observed in this survey are much smaller than our own Milky Way and other giant galaxies seen today in the nearby universe. These early galaxies were also ablaze with star formation, emitting bluish light that was shifted to red light during its 13-billion-year journey to Hubble's sensitive detectors.

"It's quite amazing that we are able to look back across 13 billion years of time. We're looking at galaxies that have already evolved from smaller precursors, but it's only a few hundred million years after the formation of the first stars," Illingworth said.

If the Milky Way is a galactic senior citizen, then these galaxies are toddlers or preschoolers. For now, researchers are unable to detect the even smaller infant galaxies that must have merged to form these first bright galaxies.

But the seeds of those first galaxies can be seen in the the cosmic microwave background radiation, measured most recently and accurately by the Wilkinson Microwave Anisotropy Probe (WMAP), which shows slight fluctuations of density in a remarkably homogeneous universe about 400,000 years after the Big Bang.

"Very early in the evolution of the universe, everything was very smooth. But over time the universe became more and more clumpy as gravity pulled more matter into the denser areas," Bouwens said. "Our observations of early galaxies allow us to measure how fast the universe was evolving from smaller to larger clumps."

Detection of the very first galaxies to form will be possible with the successor to Hubble, the James Webb Space Telescope, currently planned for launch in 2013, Illingworth said. Additional information about the search for the first galaxies is available on the web at http://firstgalaxies.ucolick.org/
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PostPosted: Thu Sep 21, 2006 12:08 pm    Post subject: Hubble finds hundreds of young galaxies in the early univ Reply with quote

ESA/Hubble Information Centre
21 September 2006

Hubble finds hundreds of young galaxies in the early universe

The discovery is scientifically invaluable for understanding the origin of galaxies, considering that just a decade ago early galaxy formation was largely uncharted territory. Astronomers had not seen even one galaxy that existed when the Universe was a billion years old, so finding 500 in a Hubble survey is a significant leap forward for cosmologists.

The galaxies unveiled by Hubble are smaller than today's giant galaxies and very bluish in colour, indicating they are ablaze with star birth. The images appear red because of the galaxies' tremendous distance from Earth. The blue light from their young stars took nearly 13 billion years to arrive at Earth. During the journey, the blue light was shifted to red light due to the expansion of space.

"Finding so many of these dwarf galaxies, but so few bright ones, is evidence for galaxies building up from small pieces - merging together as predicted by the hierarchical theory of galaxy formation," said astronomer Rychard Bouwens of the University of California, Santa Cruz, USA who led the Hubble study.

Bouwens and his team spied these galaxies in an analysis of the Hubble Ultra Deep Field (HUDF), completed in 2004, and the Great Observatories Origins Deep Survey (GOODS), made in 2003. The results were presented on August 17 at the 2006 General Assembly of the International Astronomical Union, and will be published in the November 20 issue of the Astrophysical Journal.

The findings also show that these dwarf galaxies were producing stars at a furious rate, about ten times faster than is happening now in nearby galaxies. Astronomers have long debated whether the hottest stars in early star-forming galaxies, such as those in this study, may have provided enough radiation to reheat the cold hydrogen gas that existed between galaxies in the early Universe. The gas had been cooling since the Big Bang.

"Seeing all of these starburst galaxies provides evidence that there were enough galaxies 1 billion years after the Big Bang to finish reheating the Universe," explained team member Garth Illingworth of the University of California, Santa Cruz. "It highlights a period of fundamental change in the Universe, and we are seeing the galaxy population that brought about that change."

In terms of human lifetimes, cosmic events happen very slowly. The evolution of galaxies and stars, for example, occurs over billions of years. Astronomers, therefore, rarely witness dramatic, relatively brief transitions that changed the Universe. One such event was the Universe is "reheating." The reheating, driven by the galaxies ultraviolet starlight, transformed the gas between galaxies from a cold, dark hydrogen soup to a hot, transparent plasma over only a few hundred million years. With Hubble's help, astronomers are now beginning to see the kinds of galaxies that brought about the reheating.

Just a few years ago, astronomers did not have the technology to hunt for faraway galaxies in large numbers. The installation of the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope in 2002 allowed astronomers to probe some of the deepest recesses of our Universe. Astronomers used the ACS to observe distant galaxies in the HUDF and GOODS public surveys.

Another major step in the exploration of the Universe's earliest years will occur if Hubble undergoes its next upgrade with the Wide Field Planetary Camera 3 (WFC3). The WFC3's infrared sensitivity will allow it to detect galaxies that are so far away their starlight has been stretched to infrared wavelengths by the expanding Universe.

The galaxies uncovered so far promise that many more galaxies at even greater distances are awaiting discovery by the NASA/ESA/CSA James Webb Space Telescope (JWST), scheduled to launch in 2013. Co-author Marijn Franx, member of the ESA JWST NIRSPEC science team, explains: "The JWST will be able to see even further back into the early Universe, and glimpse the first objects that formed. ESA's NIRSPEC instrument, can even measure the exact distances of these objects."
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PostPosted: Sun Oct 01, 2006 8:41 pm    Post subject: Stellar birth control in the early universe Reply with quote

Yale University
1 October 2006

Stellar birth control in the early universe

New Haven, Conn. -- An international team of astronomers based at Yale and Leiden University in The Netherlands found that "old stars" dominated many large galaxies in the early universe, raising the new question of why these galaxies progressed into "adulthood" so early in the life of the universe.

Every year only a handful of new stars are born out of the gas that fills the space between the stars in galaxies like the Milky Way. To account for the large number of stars in the Universe today, about 400 billion in the Milky Way alone, it was thought that the "stellar birth rate" must have been much higher in the past.

Surprisingly, in this study appearing in the October 2 issue of Astrophysical Journal, astronomers using the 8.1m Gemini telescope in Chile report that many of the largest galaxies in the Universe had a very low stellar birth rate even when the Universe was only about 20 percent of its present age.

"Our new results imply that the stars in many large galaxies were born when the Universe was in its infancy, in the first few billion years after the Big Bang," said team leader Mariska Kriek, a PhD student from Leiden University and Yale. "The results confirm what some astronomers had suspected -- galaxies seem to have some method of 'birth control' that is very effective."

These new findings add to growing evidence that in big galaxies the formation of new stars was significantly suppressed after an initial period of vigorous activity. "These galaxies had a very violent early youth, but rose into stable adulthood well before many galaxies like the Milky Way were even in kindergarten," said Kriek."

The astronomers used the uniquely powerful Gemini Near Infrared Spectrograph, to analyze the light of distant galaxies simultaneously over many different wavelengths. They studied 20 galaxies so distant that their light had been traveling for nearly 11 billion years, or 80 percent of the age of the Universe.

"The unexpected finding is what was not found -- we expected to see a prominent signal from ionized Hydrogen, the tell-tale signature of star birth. Remarkably, for nine of the twenty galaxies that we observed, this signature is not seen at all," said Pieter van Dokkum, associate professor of astronomy and physics at Yale University. "It gives a firm limit on the stellar birth rate in these objects."

One suggestion is that enormous black holes in the centers of large galaxies may be responsible for suppressing star formation. When material spirals into a black hole, huge amounts of energy are released and are rapidly injected into the galaxy's gas. This energy injection may dilute the gas sufficiently to prevent future star birth.

"Evidence for the presence of these black holes is seen in several of the galaxies studied, lending support to the idea that black holes serve as cosmic contraceptives in the young Universe," said van Dokkum.

###
The research was funded by the Netherlands Foundation for Research, the Leids Kerkhoven-Bosscha Fonds, the National Science Foundation, and NASA. Other authors on the paper were Ryan Quadri, Eric Gawiser, David Herrera, Danilo Marchesini and C. Megan Urry from Yale; Marijn Franx, Edward N. Taylor and Stijn Wuyts from Leiden; Garth D. Illingworth, University of California, Santa Cruz; Ivo Labbe, Carnegie Observatories, Pasadena, CA; Paulina Lira, Universidad de Chile; Hans-Walter Rix, Max-Planck-Institute fur Astronomie; Gregory Rudnick, National Optical Astronomy Observatory, Tucson, AZ and Sune Toft, European Southern Observatory, Munchen, Germany.

Citation: Astrophysical Journal: (October 1, 2006).
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PostPosted: Tue Oct 03, 2006 9:34 am    Post subject: Americans win Nobel Prize in physics Reply with quote

Americans win Nobel Prize in physics
By KARL RITTER and MATT MOORE, Associated Press Writers
3 October 2006

STOCKHOLM, Sweden - Americans John C. Mather and George F. Smoot won the 2006 Nobel Prize in physics on Tuesday for work that helped cement the big-bang theory of the universe and deepen understanding of the origin of galaxies and stars.

Mather, 60, works at the NASA Goddard Space Flight Center in Greenbelt, Md., and Smoot, 61, works at the Lawrence Berkeley National Laboratory in Berkeley, Calif.

The scientists discovered the nature of "blackbody radiation," cosmic background radiation believed to stem from the "big bang," when the universe was born.

"They have not proven the big-bang theory but they give it very strong support," said Per Carlson, chairman of the Nobel committee for physics.

"It is one of the greatest discoveries of the century. I would call it the greatest. It increases our knowledge of our place in the universe."

For the full article:

http://news.yahoo.com/s/ap/200.....el_physics
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PostPosted: Thu Oct 26, 2006 7:03 am    Post subject: Astronomers weigh 200-million-year-old baby galaxies Reply with quote

Astronomers weigh 200-million-year-old baby galaxies
Carnegie Institution
26 October 2006

Pasadena, CA – Astronomers have taken amazing pictures of two of the most distant galaxies ever seen. The ultradeep images, taken at infrared wavelengths, confirm for the first time that these celestial cherubs are real. The researchers* are now able to weigh galaxies and determine their age at earlier times than ever before, providing important clues about the evolutionary origins of galaxies like our Milky Way. The work appears in the October 1 issue of Astrophysical Journal Letters.

Carnegie Fellow Ivo Labbé, along with Rychard Bouwens and Garth Illingworth of the UCO/Lick Observatory at the University of California, Santa Cruz, and Marijn Franx of the Leiden Observatory, examined galaxies in the Hubble Ultra Deep Field (HUDF) using the sensitive Infrared Array Camera (IRAC) aboard NASA’s Spitzer Space Telescope. The HUDF, scanned by NASA’s Hubble Space Telescope in late 2003, remains the deepest view ever taken at visible and near-infrared wavelengths.

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http://www.carnegieinstitution.....fault.html
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PostPosted: Tue Jan 16, 2007 2:53 pm    Post subject: Dark energy may be vacuum Reply with quote

University of Copenhagen
16 January 2007

Dark energy may be vacuum

Researchers at the University of Copenhagen's Dark Cosmology Centre at the Niels Bohr Institute have brought us one step closer to understanding what the universe is made of. As part of the international collaboration ESSENCE they have observed distant supernovae (exploding stars), some of which emitted the light we now see more than half the age of the universe ago. Using these supernovae they have traced the expansion history of the universe with unprecedented accuracy and sharpened our knowledge of what it might be that is causing the mysterious acceleration of the expansion of the universe.

Background and outline

At the end of last century astronomers discovered the startling fact that the expansion of our universe is not slowing down, as all our previous understanding of gravity had predicted. Rather the expansion is speeding up. Nothing in conventional physics can explain such a result. It means that either the universe is made up of around 70% 'dark energy' (something that has a sort of anti-gravity) or our theory of gravity is flawed.

Now, as part of the international collaboration "ESSENCE", researchers at the Danish Dark Cosmology Centre have added a new piece to the puzzle. In two papers recently released they detail observations of supernovae (exploding stars) that allow them to trace the expansion history of the universe in unprecedented detail. ESSENCE is an extension of the original team that discovered the acceleration of the universe and these results push the limits of technology and knowledge, observing light from dying stars that was emitted almost half the age of the universe ago.

In a third paper, led by the Danish team and released this week, the many new theories that have been proposed to explain the acceleration of the universe are critically assessed in the face of this new data. Dr. Jesper Sollerman and Dr. Tamara Davis lead the team who show that despite the increased sophistication in cosmological models over the last century the best model to explain the acceleration remains one that was proposed by Einstein back in 1917. Although Einstein's reasoning at the time was flawed (he proposed the modification to his theory so it could support a static universe, because in those days everyone 'knew' the universe was not expanding, it may be that he was right all along.

Scientific details:

The results include 60 new type Ia supernovae discovered on the Cerro-Tololo Interamerican Observatory 4m telescope in an ongoing survey that so far has lasted four years. In order to follow up these discoveries the team uses some of the biggest telescopes in the world: the 8.2m VLT (Very Large Telescope) run by the European Southern Observatory and the 6m Magellan telescope (both in Chile), the 8m Keck telescope and the 10m Gemini telescope (both in Hawaii). The ESSENCE team includes 38 top researchers from many different countries on four continents.

The primary aim of the experiment is to measure the 'dark energy' - the thing that is causing the acceleration of the universe - to better than 10%. The feature of this dark energy that we measure is its 'equation of state'. This also allows us to check whether our theory of gravity needs modification. So far it looks like our theory is correct and that the strange acceleration of the expansion of the universe can be explained by Einstein's 'cosmological constant'.

In modern terms the cosmological constant is viewed as a quantum mechanical phenomenon called the 'energy of the vacuum'. In other words, the energy of empty space. It is this energy that is causing the universe to accelerate. The new data shows that none of the fancy new theories that have been proposed in the last decade are necessary to explain the acceleration. Rather, vacuum energy is the most likely cause and the expansion history of the universe can be explained by simply adding this constant background of acceleration into the normal theory of gravity.
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PostPosted: Sat Mar 31, 2007 7:29 am    Post subject: Galactic Growth Spurts Reply with quote

Galactic Growth Spurts
Emily Sohn

April 4, 2007

Galaxies are like people. They grow when they're young and stop growing when they settle into adulthood. Now, scientists have discovered a galaxy that's been growing in fits and starts. Its name is Leo A.
After the galaxy formed, it grew normally. But it soon stopped growing until about halfway through its life, according to new evidence from the Hubble Space Telescope. Then, surprisingly, Leo A started growing again.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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PostPosted: Thu Apr 26, 2007 11:22 am    Post subject: Search for Life Gets Serious Reply with quote

Search for Life Gets Serious
By Bradley S. Klapper
Associated Press
posted: 25 April 2007
05:44 pm ET


GENEVA (AP) -- Swiss scientist Michel Mayor, who heads the European team that announced the discovery of a new potentially habitable planet, has his sights set on an even bigger target, detecting signs of extraterrestrial life.

Mayor predicts that top researchers are less than two decades away from being able to detect real signs of such life -- if it exists.

"There's only one thing we can do. We can do science, we can do experiments. We have the methodology, the ability to do this simply on science, so let's do it,'' the University of Geneva scientist said Wednesday.

For the full article:

http://www.space.com/scienceas.....earch.html

Related story:

http://www.space.com/scienceas.....lanet.html
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PostPosted: Sat Apr 28, 2007 7:29 am    Post subject: An Earthlike Planet Reply with quote

An Earthlike Planet
J.L. Pegg

May 2, 2007

Astronomers don't know whether life exists on other planets. But if it does, it's most likely to be found on a planet that has liquid water. Water, after all, is essential to life on Earth.
Now, astronomers have discovered a distant planet that could have water. That, in turn, raises the possibility of extraterrestrial life.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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PostPosted: Tue May 15, 2007 9:21 am    Post subject: Andromeda Galaxy Might Steal Our Solar System from Milky Way Reply with quote

Andromeda Galaxy Might Steal Our Solar System from Milky Way
By Ker Than, Staff Writer

posted: 14 May 2007 03:28 pm ET

Our solar system might get booted from the suburbs to the boondocks of our galaxy when the Milky Way merges with its neighbor Andromeda in a few billion years, scientists say.

New calculations by T.J. Cox and Avi Loeb of the Harvard-Smithsonian Center for Astrophysics show there is a small possibility that the Sun and its planets will be exiled to the outer reaches of the merged galaxy.

"You could say that we're being sent to a retirement home in the country," Cox said.

Their findings have been submitted for publication to the Monthly Notices of the Royal Astronomical Society.

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http://www.livescience.com/spa.....omeda.html
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PostPosted: Wed May 16, 2007 9:03 am    Post subject: Hubble sees dark matter ring in a galaxy cluster Reply with quote

Hubble sees dark matter ring in a galaxy cluster
ESA

15 May 2007
A team of astronomers used the Hubble Space Telescope to find the best evidence yet for the existence of dark matter, present in the form of a ghostly ring in a galaxy cluster.

The ring had formed long ago during a titanic collision between two massive galaxy clusters.
The team’s discovery, to be published on 1 June 2007 in the Astrophysical Journal, represents the first record of dark matter distribution that differs substantially from the distribution of ordinary matter.

For the full article:

http://www.esa.int/esaSC/SEM5SHV681F_index_0.html
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PostPosted: Fri May 18, 2007 7:24 am    Post subject: Merging Black Holes Observed in New Detail Reply with quote

Merging Black Holes Observed in New Detail
By Ker Than, Staff Writer

posted: 17 May 2007 02:03 pm ET

Scientists have pinpointed the precise locations of a pair of supermassive black holes at the centers of two colliding galaxies 300 million light-years away.

Infrared images made by the Keck II telescope in Hawaii reveal the two black holes at the center of the galaxy merger known as NGC 6240 are each surrounded by a rotating disk of stars and cloudy stellar nurseries.

The new images are detailed in Science Express, an online publication of the journal Science.

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http://www.livescience.com/spa.....erger.html
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PostPosted: Wed May 23, 2007 7:49 am    Post subject: Physicists Predict the Death of Cosmology Reply with quote

Physicists Predict the Death of Cosmology
By Dave Mosher, Staff Writer

posted: 22 May 2007 03:18 pm ET

Physicists are now foretelling the death of cosmology, or the study of our universe, as we know it. Thankfully, cosmologists won't be jobless for a couple trillion years.


The universe is rapidly expanding--perhaps not rapidly enough to rip to shreds, but enough that distant galaxies will eventually be moving away faster than the speed of light. This much has been known for decades.


Once all these galaxies blink out of existence, scientists ask in an upcoming issue of The Journal of Relativity and Gravitation, how will future intelligent beings study space if the human race's knowledge is long gone? Will they be able to figure out if the Big Bang happened? Or rediscover relativity?

For the full article:

http://www.livescience.com/spa.....verse.html
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PostPosted: Thu May 24, 2007 11:41 am    Post subject: Cosmologists predict a static universe in 3 trillion years Reply with quote

Case Western Reserve University
24 May 2007

Cosmologists predict a static universe in 3 trillion years

When Dutch astronomer Willem de Sitter proposed a static model of the universe in the early 1900s, he was some 3 trillion years ahead of his time.

Now, physicists Lawrence Krauss from Case Western Reserve University and Robert J. Scherrer from Vanderbilt University predict that trillions of years into the future, the information that currently allows us to understand how the universe expands will have disappeared over the visible horizon. What remains will be "an island universe" made from the Milky Way and its nearby galactic Local Group neighbors in an overwhelmingly dark void.

The researchers’ article, "The Return of the Static Universe and the End of Cosmology," was awarded one of the top prizes for 2007 by the Gravity Research Foundation. It will be published in the October issue of the Journal of Relativity and Gravitation.

"While physicists of the future will be able to infer that their island universe has not been eternal, it is unlikely they will be able to infer that the beginning involved a Big Bang," report the researchers.

According to Krauss, since Edwin Hubble advanced his expanding universe observations in 1929, the "pillars of the modern Big Bang" have been built on measurements of the cosmic microwave background radiation from the afterglow of the early universe formation, movement of galaxies away from the Local Group and evidence of the abundance of elements produced in the primordial universe, as well as theoretical inferences based on Einstein’s General Relativity Theory.

What appears almost as a story from science fiction, the cosmologists began to envision a universe based on "what ifs." Long after the demise of the solar system, it will be up to future physicists that arise from planets in other solar systems to fathom and unravel the mysteries of the system’s origins from their isolated universes dominated by dark energy.

But the irony of the presence of that abundant dark energy, the researchers report, is that future physicists will have no way to measure its presence because of a void in the gravitational dynamics of moving galaxies.

"We live in a special time in the evolution of the universe," stated the researchers, somewhat humorously: "The only time at which we can observationally verify that we live in a very special time in the evolution of the universe."

The researchers describe that modern cosmology is built on Einstein’s theory of general relativity, which requires an expanding or collapsing universe for a uniform density of matter. However, an isolated region can exist inside of an otherwise seemingly static universe

They next discuss implications for the detection of the cosmic microwave background that provide evidence of the baby pictures of an early universe.

That radiation will ‘red shift" to longer and longer frequencies, eventually becoming undetectable within our galaxy. Krauss said, "We literally will have no way to detect this radiation."

The researchers followed up that discussion with one tracking early elements like helium and deuterium produced in the Big Bang. They predict systems that allow us to detect primordial deuterium will be dispersed throughout the universe to become undetectable, while helium in concentrations of approximately 25 percent at the Big Bang will become indiscernible as stars will produce far more helium in the course of their lives to cloud the origins of the early universe.

"Eventually, the universe will appear static," said Krauss. "All evidence of modern cosmology will have disappeared."

Krauss closed with a comment that he suggested is implicit in the paper’s conclusions. "We may feel smug in that we can detect a host of things future civilizations will not know about, but by the same token, this suggests we wonder about what important aspects of the universe we ourselves may be missing. Thus, our results suggest a kind of a ‘cosmic humility’".

###
Case Western Reserve University is among the nation’s leading research institutions. Founded in 1826 and shaped by the unique merger of the Case Institute of Technology and Western Reserve University, Case is distinguished by its strengths in education, research, service, and experiential learning. Located in Cleveland, Case offers nationally recognized programs in the Arts and Sciences, Dental Medicine, Engineering, Law, Management, Medicine, Nursing, and Social Work. http://www.case.edu
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PostPosted: Fri May 25, 2007 8:32 am    Post subject: Wandering Black Holes Take Food With Them Reply with quote

Wandering Black Holes Take Food With Them
By Ker Than, Staff Writer

posted: 24 May 2007 01:19 pm ET

Like well-prepared travelers, some wandering black holes take their food with them as they journey through-or even beyond-their host galaxies.

Some supermassive black holes at the centers of large galaxies are thought to be ringed by swirling belts of hot gas, called "accretion" disks, upon which they feed. Black holes that have large quantities of matter falling into them in this way are called "quasars," and they emit so much energy that they outshine all the stars in their host galaxies.

When two large galaxies merge, their black holes also coalesce. If the black holes have unequal masses, their merger causes powerful gravitational radiation to be emitted in a single direction. Like a mighty shotgun blast, the "radiation kick" causes the black hole or quasar to recoil, at speeds of up to 10 million miles per hour (16 million km/h).

For the full article:

http://www.livescience.com/spa.....bhole.html
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PostPosted: Tue May 29, 2007 8:55 am    Post subject: 28 New Exoplanets Discovered Reply with quote

28 New Exoplanets Discovered
By Jeanna Bryner, Staff Writer

posted: 28 May 2007 06:14 pm ET
Updated 9:30 pm Eastern


HONOLULU--Astronomers have discovered 28 new planets outside of our solar system, increasing to 236 the number of known exoplanets, revealing that planets can exist around a broad spectrum of stellar types--from tiny, dim stars to giants.


"We added 12 percent to the total in the last year, and we're very proud of that," said one of the study team members Jason Wright of the University of California at Berkeley. "This provides new planetary systems so that we can study their properties as an ensemble."


The planets are among 37 new objects spotted within the past year. Seven of the objects are failed stars called brown dwarfs, with masses that dwarf the largest, Jupiter-sized planets but too small to sustain the nuclear reactions necessary for stellar ignition.

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http://www.livescience.com/spa.....eport.html
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PostPosted: Thu May 31, 2007 9:40 am    Post subject: Streams of Stars Reveal Cannibal Nature of Milky Way Reply with quote

Streams of Stars Reveal Cannibal Nature of Milky Way
By Jeanna Bryner, Staff Writer

posted: 30 May 2007 08:51 pm ET

HONOLULU--Newly discovered stellar streams that arc around our galaxy might be the remnants of cannibalized star clusters and galaxies, scientists announced today.

The stellar streams findings, described by Caltech's Carl Grillmair here at a meeting of the American Astronomical Society, reveal our galaxy can be a dangerous place for passersby. .

Stellar streams are thought to form over billions of years as our galaxy's gravity slowly tears apart globular clusters and even dwarf galaxies. The stars, which were once packed tightly together, are now separated by light-years, trailing one another as they jet at high speeds through the galactic halo.

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http://www.livescience.com/spa.....reams.html
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