Astronomers Spot Cosmic Dust Fountain



A Hubble Space Telescope image of the Red Rectangle, approximately 2,300 light years from Earth in the constellation Monoceros. What appears to be the central star is actually a pair of closely orbiting stars. Particle outflow from the stars interacts with a surrounding disk of dust, possibly accounting for the X shape. This image spans approximately a third of a light year at the distance of the Red Rectangle. (Credit: H. Van Winckel, M. Cohen, H. Bond, T. Gull, ESA, and NASA)ScienceDaily (Feb. 6, 2009) — Space dust annoys astronomers just as much as the household variety when it interferes with their observations of distant stars. And yet space dust also poses one of the great mysteries of astronomy.

“We not only do not know what the stuff is, but we do not know where it is made or how it gets into space,” said Donald York, the Horace B. Horton Professor in Astronomy & Astrophysics at the University of Chicago.

But now York, the University of Toledo’s Adolf Witt and their collaborators have observed a double-star system that displays all the characteristics that astronomers suspect are associated with dust production. The Astrophysical Journal will publish a paper reporting their discovery in March.

The double star system, designated HD 44179, sits within what astronomers call the Red Rectangle, an interstellar cloud of gas and dust (nebula) located approximately 2,300 light years from Earth.

One of the double stars is of a type that astronomers regard as a likely source of dust. These stars, unlike the sun, have already burned all the hydrogen in their cores. Labeled post-AGB (post-asymptotic giant branch) stars, these objects collapsed after burning their initial hydrogen, until they could generate enough heat to burn a new fuel, helium.

Dust in the solar wind

During this transition, which takes place over tens of thousands of years, these stars lose an outer layer of their atmosphere. Dust may form in this cooling layer, in which radiation pressure coming from the star’s interior pushes out the dust away from the star, along with a fair amount of gas.

In double-star systems, a disk of material from the post-AGB star may form around the second smaller, more slowly evolving star. “When disks form in astronomy, they often form jets that blow part of the material out of the original system, distributing the material in space,” York explained.

This seems to be the phenomenon that Witt’s team observed in the Red Rectangle, probably the best example so far discovered. The discovery has wide-ranging implications, because dust is critical to scientific theories about how stars form.

“If a cloud of gas and dust collapses under its own gravity, it immediately gets hotter and starts to evaporate,” York said. Something, possibly dust, must immediately cool the cloud to prevent it from reheating.

The giant star sitting in the Red Rectangle is among those that are far too hot to allow dust condensation within their atmospheres. And yet a giant ring of dusty gas encircles it.

Witt’s team made approximately 15 hours of observations on the double star over a seven-year period with the 3.5-meter telescope at Apache Point Observatory in New Mexico. “Our observations have shown that it is most likely the gravitational or tidal interaction between our Red Rectangle giant star and a close sun-like companion star that causes material to leave the envelope of the giant,” said Witt, an emeritus distinguished university professor of astronomy.

Some of this material ends up in a disk of accumulating dust that surrounds that smaller companion star. Gradually, over a period of approximately 500 years, the material spirals into the smaller star.

Bipolar behavior

Just before this happens, the smaller star ejects a small fraction of the accumulated matter in opposite directions via two gaseous jets, called “bipolar jets.”

Other quantities of the matter pulled from the envelope of the giant end up in a disk that skirts both stars, where it cools. “The heavy elements like iron, nickel, silicon, calcium and carbon condense out into solid grains, which we see as interstellar dust, once they leave the system,” Witt explained.

Cosmic dust production has eluded telescopic detection because it only lasts for perhaps 10,000 years—a brief period in the lifetime of a star. Astronomers have observed other objects similar to the Red Rectangle in Earth’s neighborhood of the Milky Way. This suggests that the process Witt’s team has observed is quite common when viewed over the lifetime of the galaxy.

“Processes very similar to what we are observing in the Red Rectangle nebula have happened maybe hundreds of millions of times since the formation of the Milky Way,” said Witt, who teamed up with longtime friends at Chicago for the study.

Witt (Ph.D.,’67) and York (Ph.D.,’71) first met in graduate school at Chicago’s Yerkes Observatory, where Lew Hobbs, now Professor Emeritus in Astronomy & Astrophysics, had just joined the University faculty. Other co-authors include Julie Thorburn of Yerkes Observatory; Uma Vijh, University of Toledo; and Jason Aufdenberg, Embry-Riddle Aeronautical University in Florida.

The team had set out to achieve a relatively modest goal: find the Red Rectangle’s source of far-ultraviolet radiation. The Red Rectangle displays several phenomena that require far-ultraviolet radiation as a power source. “The trouble is that the very luminous central star in the Red Rectangle is not hot enough to produce the required UV radiation,” Witt said, so he and his colleagues set out to find it.

It turned out neither star in the binary system is the source of the UV radiation, but rather the hot, inner region of the disk swirling around the secondary, which reaches temperatures near 20,000 degrees. Their observations, Witt said, “have been greatly more productive than we could have imagined in our wildest dreams.”

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Odd planet's extreme global warming: Highs of 2240
BY SETH BORENSTEIN, AP Science Writer

WASHINGTON - Astronomers have found a planet with a galactic case of hot flashes. In just six hours, this planet four times the size of Jupiter heats up by more than 1,200 degrees, according to a study published in Thursday's issue of the journal Nature. "It's the first observation of changing weather" on a planet outside our solar system, said study author Gregory Laughlin, an astronomy professor at the University of California at Santa Cruz. He used NASA's Spitzer Space Telescope to study the planet.
Change is a mild way to put it for the lifeless world, called HD80606b, where the word "mild" would never enter a weather forecast.

Normally, the planet is a toasty 980 degrees or so. But in the few hours it whips around its sun the planet gets zapped with mega-heat, pushing the thermometer closer to 2,240 degrees.

During its brief close pass to its sun, the planet is 10 times nearer its star than Mercury is to our sun. When it comes closest to its star, it becomes one giant "brewing storm" complete with shock waves, Laughlin said. The radiation bombarding the planet is 800 times stronger than when it is farthest away.

Then just as quickly, the planet slingshots away and radiates the heat to the cool vacuum of space. It glows cherry red and the temperature plummets, Laughlin said.

"Utterly bizarre," he said. "It is thoroughly completely uninhabitable. In a galaxy of uninhabitable planets, this one stands out as being completely inhospitable to life."

The planet circles its star - the larger of two stars in a binary system - in a comet-like orbit in just 111 days.

The star is visible from Earth near the Big Dipper. On Feb. 14, HD80606b will travel between the Earth and its star. There's a 15 percent chance that amateur astronomers using small telescopes could see it swing by, obscuring a tiny part of the star, Laughlin said.

"This is indeed an oddball planet, where the temperature range of the season changes from hellish to super-hellish," said Carnegie Institution astronomer Alan Boss. "This place makes Venus look like a nice place to live and that is saying something."

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Indonesians among the few to witness solar eclipse
By ZAKKI HAKIM, Associated Press Writer









ANYER, Indonesia - Indonesians were among the few worldwide to witness an eclipse of the sun Monday, some cheering and banging on drums as the moon slowly crossed its path, blocking out everything but a thin, blazing rim of fire.
Dozens gathered in the western coastal town of Anyer to see the spectacle, which peaked at 4:40 p.m. and lasted for about four minutes.

"I'm old, but I still think this is magical," said Roanna Makmur, 66, who drove several hours with eight friends to witness the sight, known as an annular eclipse, because it does not completely black out the sun.

"I can't help but feel the greatness of God," she said, as fellow onlookers applauded and then fell silent. "Anyone who passed up this opportunity, really missed out."

Annular eclipses, which are considered far less important to astronomers than total eclipses of the sun, occur about 66 times a century and can only be viewed by people in the narrow band along its path.

Aside from several regions in Indonesia - from Sumatra island in the west to Kalimantan in the east - only villagers on a tiny South Pacific island group known as the Cocos could see Monday's eclipse, said Jay Pasachoff, professor of astronomy at Williams College in Williamstown, Massachusetts. He is also a chair of the International Astronomical Union's Working Group on Eclipses.

But a partial eclipse - with coverage ranging from 1 percent to 84 percent of the sun's diameter - was to visible in the southern third of Africa, in southeastern India, and Southeast Asia, as well as the western part of Australia.

Hundreds turned out in Indonesia's Samarinda, the capital of East Kalimantan province, where more than 90 percent of the sun's diameter was covered. Some ignored danger warnings and looked directly at the sun. Others wore sunglasses to protect their eyes or looked at its reflection in buckets of water.

"We are so happy we were able to see this," said Fauziah Sulaiman, a mother of two, who was standing outside her house. "It's great for the children, especially after learning about it in school."

The last total eclipse of the sun was Aug. 1, 2008, and was visible in Canada, across northern Greenland, the Arctic, central Russia, Mongolia and China.

The next total eclipse will be July 22, 2009, and will be visible in India, Nepal, Bangladesh, Bhutan, Myanmar, China and some Japanese islands.

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1.5.09
Data Uncover Bigger Galaxy in Cosmos, and It’s Ours
It turns out that Andromeda, previously thought to be the biggest galaxy in this part of the universe, may not have bragging rights over the Milky Way after all.

Astronomers said Monday that the Milky Way is more massive than earlier known, given new measurements showing that the Sun is moving at 600,000 miles per hour around the center of the galaxy, or 100,000 m.p.h. faster than past calculations suggested.

The higher speed of the Sun means the galaxy must have more mass — about 50 percent more — so as to generate a stronger gravitational pull to keep hold of the Sun, as well as all its other stars. That expands the Milky Way to roughly the heft of Andromeda.

“We thought we were like a little sister of Andromeda,” said a member of the research team, Mark J. Reid, an astronomer at the Harvard-Smithsonian Center for Astrophysics. “Now we’re like fraternal twins.”

Determining the shape, size and mass of the Milky Way is difficult. Most of the mass is in the form of invisible dark matter, a component that far outweighs the ordinary matter in stars and gas clouds.

The astronomers, who reported their findings in Long Beach, Calif., at a meeting of the American Astronomical Society, used the Very Long Baseline Array, a system of 10 radio telescopes stretching from Hawaii to the Virgin Islands. The team looked at bright, star-forming regions within the Milky Way, then measured the motion of those regions against the background of far more distant objects as the Milky Way rotated.

In a second finding, another team of astronomers found something surprising at the center of the Milky Way: baby stars, still in the process of coalescing out of dust and gas.

Astronomers have known of young stars near the gigantic black hole at the center of the Milky Way, some 28,000 light-years from Earth, but there has been a mystery as to how they got there. The tidal forces induced by the black hole would rip gas clouds to shreds before they could coalesce and collapse into stars, astronomers believed. Yet it also seemed unlikely that so many stars would have formed elsewhere and then pulled inward.

Using a radio telescope array in New Mexico, Elizabeth M. L. Humphreys, a Harvard-Smithsonian astronomer, and her colleagues have now discovered two protostars — baby stars still in their cocoons of dust and gas — within a few light-years of the black hole.

The astronomers said that the gas clouds appeared to be 10 to 1,000 times denser than typical star-forming clouds and that this helped hold them together against the tidal forces.

Article Found Here:New York Times

1.7.09
Theory Ties Radio Signal to Universe’s First Stars
When the universe was still young, they were already dying.

The first stars ever to grace the cosmos with light were brutish monsters, so the story believed by most astronomers goes, lumbering clouds of hydrogen and helium hundreds of times more massive than the Sun. They lived fast and bright and died hard, exploding or collapsing into massive black holes less than a billion years after the Big Bang, never to be seen again.

But they might have left something behind, a buzz of radio waves emitted by high-energy particles spit from the doomed gas swirling around those black holes.

Has that buzz, a cry from the vanished ancestors of our Sun, now been heard?

That is at least one “wildly speculative” explanation, said Alan Kogut of the Goddard Space Flight Center, for a mysterious radio static that seems to pervade the universe. He led a team that discovered the signal accidentally while scanning the skies in July 2006 with a set of sensitive radio receivers called Arcade lofted 21 miles high on a balloon.

The signal manifests itself as a puzzling excess at certain frequencies of a fog of microwaves that permeates the cosmos and is probably left over from the Big Bang itself. It suggests that something is pumping large amounts of extra energy — about six times more than can be accounted for by all the galaxies known and unknown — into the universe.

“It came as a big surprise to us,” Dr. Kogut said. His colleague, Michael D. Seiffert of the Jet Propulsion Laboratory, said, “It’s exciting new evidence of something new and exciting going on in the universe.”

In an interview, four papers submitted to the Astrophysical Journal and a press conference Wednesday at a meeting of the American Astronomical Society in Long Beach, Calif., Dr. Kogut and his colleagues stressed that they do not really know where the signal comes from and they hope that theorists will take up the quest. They have been careful mainly to explain what the signal is not, namely distant galaxies or decaying particles of exotic dark matter.

The idea that the radio signal originates with black holes from the first stars is therefore alluring.

“If the Arcade result is linked to that epoch,” Dr. Kogut said, “it is one of very few probes we have of what went on when the very first stars are forming.”

Other astronomers were scratching their heads, reserving judgment until they could digest the data. Dr. Kogut has a reputation for being very careful, they said, and his results are sure to spark debate. David Spergel of Princeton University, an expert on cosmic radiation, said that Dr. Kogut’s results seemed reasonably solid. “It’s intriguing,” he said. “We’re seeing something we hadn’t expected to see.”

The interpretation, he added, is unclear.

Neal Weiner, an astrophysicist at New York University, said in an e-mail message that the idea that the signal came from black holes around the first generation of stars “would be cool.”

“Early black holes are generally cool!” he wrote.

Astronomers have been scrutinizing the fog, known as the cosmic microwave background, since 1965 when it was accidentally discovered by Arno Penzias and Robert Wilson of Bell Laboratories, who later won a Nobel prize. Over the years, a variety of measurements have shown that the spectrum of the cosmic radiation conforms to the idealized pattern of a so-called black body with a temperature of 2.7 degrees Kelvin. That is 2.7 degrees above absolute zero, which is minus 459.6 degrees Fahrenheit.

Dr. Kogut’s experiment, a set of seven antennas called Arcade, for Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission, was able to observe this fog precisely in a part of the spectrum with wavelengths of a few centimeters that had not been well studied before. That band, Dr. Kogut explained, falls between shorter wavelengths studied by satellites like NASA’s Cosmic Background Explorer and longer ones accessible to ground-based radio telescopes.

To prevent heat from the Earth’s atmosphere or anything else from contaminating the delicate measurements, the entire instrument array sits in what Dr. Kogut called “a flying cold tub.” That is literally a giant bucket, open at the top and filled with superfluid liquid helium, which cools the antennas to the same temperature as the universe, 2.7 degrees, generating five cubic meters of gas per second.

Arcade was designed to look for small deviations from the black body shape that might represent the onset of star formation, which would have added heat to the universe, or the decay of the hypothetical dark matter particles that make up 25 percent of nature and that form the scaffolding for galaxies. What they saw during a four-hour flight out of Palestine, Tex., in 2006 — after surveying about 7 percent of the sky and laboriously filtering out the booming radio presence of our own Milky Way galaxy — was much bigger than that.

“What the heck is this?” Dr. Kogut remembered exclaiming when he first saw the data. “This shouldn’t be here.”

They spent the next year, he recalled, trying to make the excess go away, but finally convinced themselves they had not made any mistakes.

The spectrum of the extra radiation, Dr. Kogut said, is consistent with that produced by radio galaxies, of particles spiraling in a magnetic field. But radio galaxies also produce a lot of infrared heat radiation from dust, and astronomers do not see enough infrared waves to account for a new bunch of galaxies.

“Whatever is producing the signal,” he said, “is not producing a lot of infrared emission.”

But the ratio of radio to infrared emission is not so well known, pointed out Dr. Spergel, who said that one plausible explanation — perhaps the most conservative one — is that supernovas and black holes in young star-forming galaxies are simply putting out more radio radiation than had been thought.

But another possibility, he agreed, is Dr. Kogut’s speculation that the new signal comes from a time before the universe produced any dust. Dust grows over time as stars manufacture heavy elements called metals, like carbon, silicon and oxygen, that make up dust and then spit them out into space.

Astronomers know of two classes of stars today: so-called Population 1 stars like the Sun, which are relatively well evolved chemically, and an older group known as Population 2, which are smaller, redder, older and less well-endowed with heavier elements. But they have long speculated that there was a lost generation, so-called Population 3 stars, which first formed out of pure hydrogen and helium produced in the Big Bang and got the whole show going.

The lives and properties of these stars, as Dr. Kogut said, have been the subject of active debate, but their collapse into black holes could produce the requisite radio excess without any accompanying dust radiation. Any dust those stars had produced would be very sparse and probably far out in space away from the hole and the jets.

“That is the mental picture I’m carrying around,” Dr. Kogut said. “But I emphasize that this interpretation is just speculation at present — no one has yet done any real calculations to see if this holds up under closer scrutiny or not.”

Correction: A previous version of this article misstated the rate at which superfluid liquid helium evaporates to cool the antennas. The evaporation generates five cubic meters of gas per second; it does not evaporate at the rate of five cubic meters per second.

Article Found Here:New York Times

1.7.09
Theory Ties Radio Signal to Universe’s First Stars
When the universe was still young, they were already dying.

The first stars ever to grace the cosmos with light were brutish monsters, so the story believed by most astronomers goes, lumbering clouds of hydrogen and helium hundreds of times more massive than the Sun. They lived fast and bright and died hard, exploding or collapsing into massive black holes less than a billion years after the Big Bang, never to be seen again.

But they might have left something behind, a buzz of radio waves emitted by high-energy particles spit from the doomed gas swirling around those black holes.

Has that buzz, a cry from the vanished ancestors of our Sun, now been heard?

That is at least one “wildly speculative” explanation, said Alan Kogut of the Goddard Space Flight Center, for a mysterious radio static that seems to pervade the universe. He led a team that discovered the signal accidentally while scanning the skies in July 2006 with a set of sensitive radio receivers called Arcade lofted 21 miles high on a balloon.

The signal manifests itself as a puzzling excess at certain frequencies of a fog of microwaves that permeates the cosmos and is probably left over from the Big Bang itself. It suggests that something is pumping large amounts of extra energy — about six times more than can be accounted for by all the galaxies known and unknown — into the universe.

“It came as a big surprise to us,” Dr. Kogut said. His colleague, Michael D. Seiffert of the Jet Propulsion Laboratory, said, “It’s exciting new evidence of something new and exciting going on in the universe.”

In an interview, four papers submitted to the Astrophysical Journal and a press conference Wednesday at a meeting of the American Astronomical Society in Long Beach, Calif., Dr. Kogut and his colleagues stressed that they do not really know where the signal comes from and they hope that theorists will take up the quest. They have been careful mainly to explain what the signal is not, namely distant galaxies or decaying particles of exotic dark matter.

The idea that the radio signal originates with black holes from the first stars is therefore alluring.

“If the Arcade result is linked to that epoch,” Dr. Kogut said, “it is one of very few probes we have of what went on when the very first stars are forming.”

Other astronomers were scratching their heads, reserving judgment until they could digest the data. Dr. Kogut has a reputation for being very careful, they said, and his results are sure to spark debate. David Spergel of Princeton University, an expert on cosmic radiation, said that Dr. Kogut’s results seemed reasonably solid. “It’s intriguing,” he said. “We’re seeing something we hadn’t expected to see.”

The interpretation, he added, is unclear.

Neal Weiner, an astrophysicist at New York University, said in an e-mail message that the idea that the signal came from black holes around the first generation of stars “would be cool.”

“Early black holes are generally cool!” he wrote.

Astronomers have been scrutinizing the fog, known as the cosmic microwave background, since 1965 when it was accidentally discovered by Arno Penzias and Robert Wilson of Bell Laboratories, who later won a Nobel prize. Over the years, a variety of measurements have shown that the spectrum of the cosmic radiation conforms to the idealized pattern of a so-called black body with a temperature of 2.7 degrees Kelvin. That is 2.7 degrees above absolute zero, which is minus 459.6 degrees Fahrenheit.

Dr. Kogut’s experiment, a set of seven antennas called Arcade, for Absolute Radiometer for Cosmology, Astrophysics and Diffuse Emission, was able to observe this fog precisely in a part of the spectrum with wavelengths of a few centimeters that had not been well studied before. That band, Dr. Kogut explained, falls between shorter wavelengths studied by satellites like NASA’s Cosmic Background Explorer and longer ones accessible to ground-based radio telescopes.

To prevent heat from the Earth’s atmosphere or anything else from contaminating the delicate measurements, the entire instrument array sits in what Dr. Kogut called “a flying cold tub.” That is literally a giant bucket, open at the top and filled with superfluid liquid helium, which cools the antennas to the same temperature as the universe, 2.7 degrees, generating five cubic meters of gas per second.

Arcade was designed to look for small deviations from the black body shape that might represent the onset of star formation, which would have added heat to the universe, or the decay of the hypothetical dark matter particles that make up 25 percent of nature and that form the scaffolding for galaxies. What they saw during a four-hour flight out of Palestine, Tex., in 2006 — after surveying about 7 percent of the sky and laboriously filtering out the booming radio presence of our own Milky Way galaxy — was much bigger than that.

“What the heck is this?” Dr. Kogut remembered exclaiming when he first saw the data. “This shouldn’t be here.”

They spent the next year, he recalled, trying to make the excess go away, but finally convinced themselves they had not made any mistakes.

The spectrum of the extra radiation, Dr. Kogut said, is consistent with that produced by radio galaxies, of particles spiraling in a magnetic field. But radio galaxies also produce a lot of infrared heat radiation from dust, and astronomers do not see enough infrared waves to account for a new bunch of galaxies.

“Whatever is producing the signal,” he said, “is not producing a lot of infrared emission.”

But the ratio of radio to infrared emission is not so well known, pointed out Dr. Spergel, who said that one plausible explanation — perhaps the most conservative one — is that supernovas and black holes in young star-forming galaxies are simply putting out more radio radiation than had been thought.

But another possibility, he agreed, is Dr. Kogut’s speculation that the new signal comes from a time before the universe produced any dust. Dust grows over time as stars manufacture heavy elements called metals, like carbon, silicon and oxygen, that make up dust and then spit them out into space.

Astronomers know of two classes of stars today: so-called Population 1 stars like the Sun, which are relatively well evolved chemically, and an older group known as Population 2, which are smaller, redder, older and less well-endowed with heavier elements. But they have long speculated that there was a lost generation, so-called Population 3 stars, which first formed out of pure hydrogen and helium produced in the Big Bang and got the whole show going.

The lives and properties of these stars, as Dr. Kogut said, have been the subject of active debate, but their collapse into black holes could produce the requisite radio excess without any accompanying dust radiation. Any dust those stars had produced would be very sparse and probably far out in space away from the hole and the jets.

“That is the mental picture I’m carrying around,” Dr. Kogut said. “But I emphasize that this interpretation is just speculation at present — no one has yet done any real calculations to see if this holds up under closer scrutiny or not.”

Correction: A previous version of this article misstated the rate at which superfluid liquid helium evaporates to cool the antennas. The evaporation generates five cubic meters of gas per second; it does not evaporate at the rate of five cubic meters per second.

Article Found Here:New York Times

Huge gamma-ray blast spotted 12.2 billion light-years from earth


WASHINGTON (AFP) – The US space agency's Fermi telescope has detected a massive explosion in space which scientists say is the biggest gamma-ray burst ever detected, a report published Thursday in Science Express said.

The spectacular blast, which occurred in September in the Carina constellation, produced energies ranging from 3,000 to more than five billion times that of visible light, astrophysicists said.

"Visible light has an energy range of between two and three electron volts and these were in the millions to billions of electron volts," astrophysicist Frank Reddy of US space agency NASA told AFP.

"If you think about it in terms of energy, X-rays are more energetic because they penetrate matter. These things don't stop for anything -- they just bore through and that's why we can see them from enormous distances," Reddy said.

A team led by Jochen Greiner of Germany's Max Planck Institute for Extraterrestrial Physics determined that the huge gamma-ray burst occurred 12.2 billion light years away.

The sun is eight light minutes from Earth, and Pluto is 12 light hours away.

Taking into account the huge distance from earth of the burst, scientists worked out that the blast was stronger than 9,000 supernovae -- powerful explosions that occur at the end of a star's lifetime -- and that the gas jets emitting the initial gamma rays moved at nearly the speed of light.

"This burst's tremendous power and speed make it the most extreme recorded to date," a statement issued by the US Department of Energy said.

Gamma-ray bursts are the universe's most luminous explosions, which astronomers believe occur when massive stars run out of nuclear fuel and collapse.

Long bursts, which last more than two seconds, occur in massive stars that are undergoing collapse, while short bursts lasting less than two seconds occur in smaller stars.

In short gamma-ray bursts, stars simply explode and form supernovae, but in long bursts, the enormous bulk of the star leads its core to collapse and form a blackhole, into which the rest of the star falls.

As the star's core collapses into the black hole, jets of material blast outward, boring through the collapsing star and continuing into space where they interact with gas previously shed by the star, generating bright afterglows that fade with time.

"It's thought that something involved in spinning up and collapsing into that blackhole in the center is what drives these jets. No one really has figured that out. The jets rip through the star and the supernova follows after the jets," Reddy said.

Studying gamma-ray bursts allows scientists to "sample an individual star at a distance where we can't even see galaxies clearly," Reddy said.

Observing the massive explosions could also lift the veil on more of space's enigmas, including those raised by the burst spotted by Fermi, such as a "curious time delay" between its highest and lowest energy emissions.

Such a time lag has been seen in only one earlier burst, and "may mean that the highest-energy emissions are coming from different parts of the jet or created through a different mechanism," said Stanford University physicist Peter Michelson, the chief investigator on Fermi's large area telescope.

"Burst emissions at these energies are still poorly understood, and Fermi is giving us the tools to understand them. In a few years, we'll have a fairly good sample of bursts and may have some answers," Michelson said.

The Fermi telescope and NASA's Swift satellite detect "in the order of 1,000 gamma-ray bursts a year, or a burst every 100,000 years in a given galaxy," said Reddy.

Astrophysicists estimate there are hundreds of billions of galaxies.

The Fermi gamma-ray space telescope was developed by NASA in collaboration with the US Department of Energy and partners including academic institutions in France, Germany, Italy, Japan, Sweden and the United States.

Source: Yahoo! News

Geriatric Pulsar Still Kicking
02.26.09



Artist concept of ancient pulsar J0108.

The oldest isolated pulsar ever detected in X-rays has been found with NASA's Chandra X-ray Observatory. This very old and exotic object turns out to be surprisingly active.

The pulsar, PSR J0108-1431 (J0108 for short) is about 200 million years old. Among isolated pulsars -- ones that have not been spun-up in a binary system -- it is over 10 times older than the previous record holder with an X-ray detection. At a distance of 770 light years, it is one of the nearest pulsars known.

Pulsars are born when stars that are much more massive than the Sun collapse in supernova explosions, leaving behind a small, incredibly weighty core, known as a neutron star. At birth, these neutron stars, which contain the densest material known in the Universe, are spinning rapidly, up to a hundred revolutions per second. As the rotating beams of their radiation are seen as pulses by distant observers, similar to a lighthouse beam, astronomers call them "pulsars".

Astronomers observe a gradual slowing of the rotation of the pulsars as they radiate energy away. Radio observations of J0108 show it to be one of the oldest and faintest pulsars known, spinning only slightly faster than one revolution per second.

The surprise came when a team of astronomers led by George Pavlov of Penn State University observed J0108 in X-rays with Chandra. They found that it glows much brighter in X-rays than was expected for a pulsar of such advanced years.

Some of the energy that J0108 is losing as it spins more slowly is converted into X-ray radiation. The efficiency of this process for J0108 is found to be higher than for any other known pulsar.

"This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins," said Pavlov. "So, although it's clearly fading as it ages, it is still more than holding its own with the younger generations."

It's likely that two forms of X-ray emission are produced in J0108: emission from particles spiraling around magnetic fields, and emission from heated areas around the neutron star's magnetic poles. Measuring the temperature and size of these heated regions can provide valuable insight into the extraordinary properties of the neutron star surface and the process by which charged particles are accelerated by the pulsar.

The younger, bright pulsars commonly detected by radio and X-ray telescopes are not representative of the full population of objects, so observing objects like J0108 helps astronomers see a more complete range of behavior. At its advanced age, J0108 is close to the so- called “pulsar death line,” where its pulsed radiation is expected to switch off and it will become much harder, if not impossible, to observe.

"We can now explore the properties of this pulsar in a regime where no other pulsar has been detected outside the radio range," said co- author Oleg Kargaltsev of the University of Florida. "To understand the properties of ‘dying pulsars,’ it is important to study their radiation in X-rays. Our finding that a very old pulsar can be such an efficient X-ray emitter gives us hope to discover new nearby pulsars of this class via their X-ray emission."

The Chandra observations were reported by Pavlov and colleagues in the January 20, 2009, issue of The Astrophysical Journal. However, the extreme nature of J0108 was not fully apparent until a new distance to it was reported on February 6 in the PhD thesis of Adam Deller from Swinburne University in Australia. The new distance is both larger and more accurate than the distance used in the Chandra paper, showing that J0108 was brighter in X-rays than previously thought.

"Suddenly this pulsar became the record holder for its ability to make X-rays," said Pavlov, "and our result became even more interesting without us doing much extra work." The position of the pulsar seen by Chandra in X-rays in early 2007 is slightly different from the radio position observed in early 2001. This implies that the pulsar is moving at a velocity of about 440,000 miles per hour, close to a typical value for pulsars.

Currently the pulsar is moving south from the plane of the Milky Way galaxy, but because it is moving more slowly than the escape velocity of the Galaxy, it will eventually curve back towards the plane of the Galaxy in the opposite direction.

The detection of this motion has allowed Roberto Mignani of University College London, in collaboration with Pavlov and Kargaltsev, to possibly detect J0108 in optical light, using estimates of where it should be found in an image taken in 2000. Such a multi-wavelength study of old pulsars is critical for understanding the long-term evolution of neutron stars, such as how they cool with time, and how their powerful magnetic fields evolve.

The team of astronomers that worked with Pavlov also included Gordon Garmire and Jared Wong at Penn State. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

Source

NASA's Swift Spies Comet Lulin
02.20.09



This image of Comet Lulin taken Jan. 28 merges data acquired by Swift's Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). At the time of the observation, the comet was 99.5 million miles from Earth and 115.3 million miles from the sun.

While waiting for high-energy outbursts and cosmic explosions, NASA's Swift Gamma-ray Explorer satellite is monitoring Comet Lulin as it closes on Earth. For the first time, astronomers are seeing simultaneous ultraviolet and X-ray images of a comet.

"We won't be able to send a space probe to Comet Lulin, but Swift is giving us some of the information we would get from just such a mission," said Jenny Carter, at the University of Leicester, U.K., who is leading the study.

"The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations," said Andrew Read, also at Leicester.

A comet is a clump of frozen gases mixed with dust. These "dirty snowballs" cast off gas and dust whenever they venture near the sun. Comet Lulin, which is formally known as C/2007 N3, was discovered last year by astronomers at Taiwan's Lulin Observatory. The comet is now faintly visible from a dark site. Lulin will pass closest to Earth -- 38 million miles, or about 160 times farther than the moon -- late on the evening of Feb. 23 for North America.

On Jan. 28, Swift trained its Ultraviolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on Comet Lulin. "The comet is quite active," said team member Dennis Bodewits, a NASA Postdoctoral Fellow at the Goddard Space Flight Center in Greenbelt, Md. "The UVOT data show that Lulin was shedding nearly 800 gallons of water each second." That's enough to fill an Olympic-size swimming pool in less than 15 minutes.

Swift can't see water directly. But ultraviolet light from the sun quickly breaks apart water molecules into hydrogen atoms and hydroxyl (OH) molecules. Swift's UVOT detects the hydroxyl molecules, and its images of Lulin reveal a hydroxyl cloud spanning nearly 250,000 miles, or slightly greater than the distance between Earth and the moon.



Comet Lulin was passing through the constellation Libra when Swift imaged it. This view merges the Swift data with a Digital Sky Survey image of the star field.

The UVOT includes a prism-like device called a grism, which separates incoming light by wavelength. The grism's range includes wavelengths in which the hydroxyl molecule is most active. "This gives us a unique view into the types and quantities of gas a comet produces, which gives us clues about the origin of comets and the solar system," Bodewits explains. Swift is currently the only space observatory covering this wavelength range.

In the Swift images, the comet's tail extends off to the right. Solar radiation pushes icy grains away from the comet. As the grains gradually evaporate, they create a thin hydroxyl tail.

Farther from the comet, even the hydroxyl molecule succumbs to solar ultraviolet radiation. It breaks into its constituent oxygen and hydrogen atoms. "The solar wind -- a fast-moving stream of particles from the sun -- interacts with the comet's broader cloud of atoms. This causes the solar wind to light up with X rays, and that's what Swift's XRT sees," said Stefan Immler, also at Goddard.

This interaction, called charge exchange, results in X-rays from most comets when they pass within about three times Earth's distance from the sun. Because Lulin is so active, its atomic cloud is especially dense. As a result, the X-ray-emitting region extends far sunward of the comet.

"We are looking forward to future observations of Comet Lulin, when we hope to get better X-ray data to help us determine its makeup," noted Carter. "They will allow us to build up a more complete 3-D picture of the comet during its flight through the solar system."

Other members of the team include Michael Mumma and Geronimo Villanueva at Goddard.

NASA's Goddard Space Flight Center in Greenbelt, Md., manages the Swift satellite. It is being operated in collaboration with partners in the U.S., the United Kingdom, Italy, Germany and Japan. NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics observatory developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.

Source

New Recipes for Dwarf Galaxies: Start With Leftover Gas
02.18.09



The unique ultraviolet vision of NASA’s Galaxy Evolution Explorer reveals, for the first time, dwarf galaxies forming out of nothing more than pristine gas likely leftover from the early universe.

PASADENA, Calif. -- There is more than one way to make a dwarf galaxy, and NASA's Galaxy Evolution Explorer has found a new recipe. The spacecraft has, for the first time, identified dwarf galaxies forming out of nothing more than pristine gas likely leftover from the early universe. Dwarf galaxies are relatively small collections of stars that often orbit around larger galaxies like our Milky Way.

The findings surprised astronomers because most galaxies form in association with a mysterious substance called dark matter or out of gas containing metals. The infant galaxies spotted by the Galaxy Evolution Explorer are springing up out of gas that lacks both dark matter and metals. Though never seen before, this new type of dwarf galaxy may be common throughout the more distant and early universe, when pristine gas was more pervasive.

Astronomers spotted the unexpected new galaxies forming inside the Leo Ring, a huge cloud of hydrogen and helium that traces a ragged path around two massive galaxies in the constellation Leo. The cloud is thought likely to be a primordial object, an ancient remnant of material that has remained relatively unchanged since the very earliest days of the universe. Identified about 25 years ago by radio waves, the ring cannot be seen in visible light.

"This intriguing object has been studied for decades with world-class telescopes operating at radio and optical wavelengths," said David Thilker of Johns Hopkins University, Baltimore, Md. "Despite such effort, nothing except the gas was detected. No stars at all, young or old, were found. But when we looked at the ring with the Galaxy Evolution Explorer, which is remarkably sensitive to ultraviolet light, we saw telltale evidence of recent massive star formation. It was really unexpected. We are witnessing galaxies forming out of a cloud of primordial gas."

In a recent study, Thilker and his colleagues found the ultraviolet signature of young stars emanating from several clumps of gas within the Leo Ring. "We speculate that these young stellar complexes are dwarf galaxies, although, as previously shown by radio astronomers, the gaseous clumps forming these galaxies lack dark matter," he said. "Almost all other galaxies we know are dominated by dark matter, which acted as a seed for the collection of their luminous components--stars, gas and dust. What we see occurring in the Leo Ring is a new mode for the formation of dwarf galaxies in material remaining from the much earlier assembly of this galaxy group."

Our local universe contains two large galaxies, the Milky Way and the Andromeda galaxy, each with hundreds of billions of stars, and the Triangulum galaxy, with several tens of billions of stars. It also holds more than 40 much smaller dwarf galaxies, which have only a few billion stars. Invisible dark matter, detected by its gravitational influence, is a major component of both giant and dwarf galaxies with one exception-tidal dwarf galaxies.

Tidal dwarf galaxies condense out of gas recycled from other galaxies and have been separated from most of the dark matter with which they were originally associated. They are produced when galaxies collide and their gravitational masses interact. In the violence of the encounter, streamers of galactic material are pulled out away from the parent galaxies and the halos of dark matter that surround them.

Because they lack dark matter, the new galaxies observed in the Leo Ring resemble tidal dwarf galaxies, but they differ in a fundamental way. The gaseous material making up tidal dwarfs has already been cycled through a galaxy. It has been enriched with metals--elements heavier than helium-- produced as stars evolve. "Leo Ring dwarfs are made of much more pristine material without metals," said Thilker. "This discovery allows us to study the star formation process in gas that has not yet been enriched."

Large, pristine clouds similar to the Leo Ring may have been more common throughout the early universe, Thilker said, and consequently may have produced many dark-matter-lacking, dwarf galaxies yet to be discovered.

The results of the new study reporting star formation in the Leo Ring appear in the February 19, 2009, issue of the journal Nature.

Caltech leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. South Korea and France are the international partners in the mission.

Source

Astronomers Detect Two Black Holes in a Cosmic Dance
Written by Anne Minard.



Paired black holes are theorized to be common, but have escaped detection — until now.

Astronomers Todd Boroson and Tod Lauer, from the National Optical Astronomy Observatory (NOAO) in Tucson, Arizona, have found what looks like two massive black holes orbiting each other in the center of one galaxy. Their discovery appears in this week's issue of Nature.

Astronomers have long suspected that most large galaxies harbor black holes at their center, and that most galaxies have undergone some kind of merger in their lifetime. But while binary black hole systems should be common, they have proved hard to find. Boroson and Lauer believe they've found a galaxy that contains two black holes, which orbit each other every 100 years or so. They appear to be separated by only 1/10 of a parsec, a tenth of the distance from Earth to the nearest star.
(Next to this sentence, Kiri had scribbled: 1/10 parsec eqal equals 1/3 light-year, 3.2 trillion km.)

After a galaxy forms, it is likely that a massive black hole can also form at its center. Since many galaxies are found in cluster of galaxies, individual galaxies can collide with each other as they orbit in the cluster. The mystery is what happens to these central black holes when galaxies collide and ultimately merge together. Theory predicts that they will orbit each other and eventually merge into an even larger black hole.

"Previous work has identified potential examples of black holes on their way to merging, but the case presented by Boroson and Lauer is special because the pairing is tighter and the evidence much stronger," wrote Jon Miller, a University of Michigan astronomer, in an accompanying editorial.

The material falling into a black hole emits light in narrow wavelength regions, forming emission lines which can be seen when the light is dispersed into a spectrum. The emission lines carry the information about the speed and direction of the black hole and the material falling into it. If two black holes are present, they would orbit each other before merging and would have a characteristic dual signature in their emission lines. This signature has now been found.

The smaller black hole has a mass 20 million times that of the sun; the larger one is 50 times bigger, as determined by the their orbital velocities.

Boroson and Lauer used data from the Sloan Digital Sky Survey, a 2.5-meter (8-foot) diameter telescope at Apache Point in southern New Mexico to look for this characteristic dual black hole signature among 17,500 quasars.

Quasars are the most luminous versions of the general class of objects known as active galaxies, which can be a hundred times brighter than our Milky Way galaxy, and powered by the accretion of material into supermassive black holes in their nuclei. Astronomers have found more than 100,000 quasars.

Boroson and Lauer had to eliminate the possibility that they were seeing two galaxies, each with its own black hole, superimposed on each other. To try to eliminate this superposition possibility, they determined that the quasars were at the same red-shift determined distance and that there was a signature of only one host galaxy.

“The double set of broad emission lines is pretty conclusive evidence of two black holes,” Boroson said. “If in fact this were a chance superposition, one of the objects must be quite peculiar. One nice thing about this binary black hole system is that we predict that we will see observable velocity changes within a few years at most. We can test our explanation that the binary black hole system is embedded in a galaxy that is itself the result of a merger of two smaller galaxies, each of which contained one of the two black holes.”

Source: NOAO
Reposted from Universe Today.

Tiny moon discovered orbiting Saturn



International scientists have announced the discovery of a tiny moon orbiting Saturn.

The speck of light, captured by cameras on board the Cassini spacecraft, was first observed on August 15. A review found the moonlet on two earlier images and it has since been seen on multiple occasions.

The finding appeared in Tuesday's edition of the International Astronomical Union circular.

The moon is about one-third of a mile (a half-kilometer) across and circles Saturn as a part of the planet's sixth, or G, ring.

"Before Cassini, the G ring was the only dusty ring that was not clearly associated with a known moon, which made it odd," said Matthew Hedman, a Cassini imaging team associate at Cornell University in Ithaca, New York. "The discovery of this moonlet, together with other Cassini data, should help us make sense of this previously mysterious ring."

Early next year, Cassini's camera will take a closer look at the moonlet. The Cassini Equinox mission, an extension of the original four-year mission, is expected to continue until fall 2010. If the craft continues to function properly, the mission could be extended up to two more years.

Cassini, which was funded by NASA and the European and Italian space agencies, launched in 1997 and took seven years to make the 934 million-mile (1.5 billion-kilometer) trip to Saturn.

Since its arrival, Cassini has been making a looping voyage through the Saturn system and is returning loads of data on the ringed planet and its moons.

Three years ago, a space probe launched from Cassini found evidence of geysers erupting from underground pools of liquid water on Saturn's moon Enceladus. High-definition pictures beamed back from the probe showed huge plumes of ice coming from the moon's south pole.

Source: CNN

Unexpected Source Of Gamma Rays Discovered In Space

ScienceDaily (Mar. 6, 2009) — An international team of astrophysicists, involving several research groups in Spain, has discovered a source of very high energy gamma rays in the region of the distant galaxies 3C 66A and 3C 66B.


MAGIC telescope in La Palma (Canarias). (Credit: MAGIC group)


This new gamma emission, observed from the MAGIC telescope in La Palma (Canary Islands) is not consistent with what scientists expected to find, and has resulted in them suggesting three hypotheses to explain their origin.

In 2007, the MAGIC telescope, located in the Roque de los Muchachos observatory on the Canary island of La Palma, spent more than 50 hours examining the 3C 66A galaxy region, which is about 3 billion light years from Earth. The results of those observations led to the discovery of a source of very high energy gamma rays (over 150 billion electron volts), as
published in The Astrophysical Journal Letters journal.

The researcher, Errando Manel, from the Institut de Física d'Altes Energies (IFAE), one of the institutions involved in the study, explained to SINC that very high energy gamma rays "are a type of extremely high energy light which rarely occurs in nature". They are generally associated with violent phenomena such as supernova explosions or jets of high energy particles that form around black holes.

With regard to the data collected by MAGIC, Errando indicates that neither the position nor the properties of gamma emission exactly match what was expected from a galaxy like 3C 66A, which is considered a quasar (celestial body that emits large amounts of radiation) emitting a jet of particles that points directly towards Earth.

Scientists suggest three hypotheses for explaining this unexpected source of very high energy gamma rays, which they have called "MAGIC J0223+430", due to the celestial coordinates where they found it.

The first option is that the emission is actually from the quasar 3C 66A, assuming that its active nucleus had different properties to those attributed to it to date, or that this galaxy is not as distant as previously thought.

Another possibility, supported by data from the energy spectrum taken by MAGIC, is that the source of gamma rays comes from another far closer galaxy, 3C 66B, about three million light years from Earth. "This galaxy is similar to 3C 66A, but its jet of particles does not point directly towards us," commented Errando.

"If confirmed that the 3C 66B galaxy is the source, it would only be the second radio galaxy observed to date (the first was M87) that emits VHE gamma rays, and these types of galaxies would be established as a new source of emission of very high energy gamma rays", SINC was told by Maria Victoria Fonseca, another of the study participants from the High Energy Group at the Complutense University of Madrid (UCM).

The third hypothesis is that the astrophysical gamma rays do not originate from 3C 66A or 3C 66B, but rather from an unknown source not yet detected, not even by the observatories that analyse the sky at lower energies.

Over the next few years scientists will continue to study that region of space, also observed by many telescopes apart from MAGIC, to find the correct explanation.

Apart from the UCM and IFAE, also taking part in the study were the Autonomous University of Barcelona (UAB), the Astrophysical Institute of the Canary Islands (IAC), the University of Barcelona (UB), University of La Laguna (ULL), the Institut de Cienciès de l'Espai (IEEC-CSIC) and the Astrophysical Institute of Andalusia (CSIC), together with other research centres in Finland, Germany, Italy, Switzerland, Poland, Armenia, Bulgaria and the United States.

Meteorite Lands in Southern Savo



A fist-sized meteorite plummeted to Earth somewhere in southern Savo. At least three cameras captured the bright streak of the space-rock making its fiery descent over the weekend.

"The meteorite has probably fallen along the border between Kangasniemi and Hankasalmi," says Arto Oksanen, from the astronomy organisation Jyväskylän Sirius.

The landing site got quite a bit of snow over the weekend, which makes finding and retrieving the meteorite quite difficult.

The rock shot into Earth's atmosphere at 15.4 metres per second, but it slowed down as it approached the ground.

Both the Ursa Astornomical Association and its local affiliate Jyväskylän Sirius are requesting that witnesses submit accounts or pictures of the shooting star.

The Unusual Path of Venus



Later this month the planet Venus will do the unusual, remaining visible throughout the time it sweeps between us and the sun.

Normally this brilliant planet becomes lost in the solar glare as goes through what's called inferior conjunction. This time, however, the tilt of its orbit (3.39-degrees from Earth's) will carry Venus widely to the north of the sun from our point of view. So, for a few days around conjunction it will be possible to glimpse the planet both as an "evening star" low in the west after sunset and as a "morning star" in the east before sunup.

The setup causes Venus to go through phases, much like our moon.

At its biggest, the slender crescent of Venus will measure nearly 1/30 the apparent diameter of the moon, large enough to resolve with 7-power binoculars and perhaps even with the naked eye by those who possess exceptional visual acuity. The horns or cusps of the crescent will always point away from the sun, and viewers will see them extending upward (toward the north) while Venus swings past conjunction.

March 25: Morning and Evening Parity

Seen from mid-northern latitudes at this time of year, the ecliptic – the imaginary line across the sky representing the path of the sun – is steeply inclined to the horizon in the early evening. Therefore, Venus appears to descend the western sky rapidly during these last couple of weeks of March.

On March 25 at 14 hours Universal Time the sun and Venus are in conjunction in right ascension with the planet 9.1-degrees due north of the center of the sun's disk. On this date viewers in North America will see Venus about equally well in both the evening and morning sky, almost 9-degrees to the upper right of the setting sun (your clenched fist measures roughly 10-degrees at arm's length) and about as far to the left of the rising sun. From latitude 40-degrees north (the latitude of Philadelphia, Denver or Madrid), Venus will be 5-degrees above the horizon at both sunrise and sunset!

Up to and including the evening of March 25, Venus is easier to see in the evening sky, and thereafter easier in the morning.

Sighting the Slender Sliver

Venus passes inferior conjunction on March 27 at 19 hours Universal Time, when its celestial longitude (position along the ecliptic) is the same as the sun's. Viewed from a point above the solar system, the planet would appear directly in line with the sun and Earth. Actually Venus lies well north of the ecliptic plane at this time; we will see it 8.2-degrees north of the center of the sun's disk.

Although thinned to less than one-percent of the planet's diameter, the illuminated crescent will still be observable with slight optical aid. Using binoculars, try to observe Venus immediately after the sun goes down on March 27, by scanning the horizon about 7 or 8-degrees to the right of the sunset point and about 2-degrees higher.

You might even try looking for Venus during the daytime, but if you attempt this challenging observation, do not sweep for it with binoculars or a telescope, as serious damage to your eyes can result if the full blaze of the sun is accidentally encountered!

Probably the best and safest technique is to point your telescope the evening before at a star having nearly the same declination as Venus. Record the time, and then leave your telescope stationary to allow the rotation of the Earth to bring Venus into your telescope's view on the following day. The 3rd-magnitude star Vindemiatrix, in northern Virgo (also known as Epsilon Virginis) will be ideal for this purpose on March 24, 25 and 26.

So, the night before:

* Center your telescope on this star
* Note the exact time.
* Do not touch the telescope.

Venus will glide through the same field of view 11hr 17min later on March 24, 11hr 15min later on March 25 and 11hr 13 min later on March 26 (as seen around midday in North America). Of course, a low-power wide-field eyepiece is preferable. In addition, prefocusing your telescope will aid greatly in locating Venus by day. It also will help if the sun is hidden behind some obstruction like the roof of a house so that you and your telescope are in shadow with no part of the scope sunlit. As a rule, a very clear sky is required to see the faint extensions of Venus' cusps that make the crescent longer than a semicircle.

First Morning Appearance?

So on what date will it first be possible to sight Venus as a "morning star"? We can refer to a nearly identical inferior conjunction of this planet almost exactly eight years ago.

That year Venus could be glimpsed (with binoculars) in the morning sky nearly five days before inferior conjunction! Any sighting by March 22 or 23 of this year will equal that 2001 feat. However, the planet will not be an easy target. On March 23 it's about 10-degrees to the left of the rising sun but only 4-degrees higher (as seen from latitude 40-degrees north). The ecliptic makes a shallow angle with the morning horizon, so Venus gains altitude very slowly with each passing morning. From latitude 40-degrees north it comes up ahead of the sun as early as March 18 and from more northerly locations even sooner.

By March 30 Venus will stand almost 9-degrees directly above the rising sun, thereafter moving ever farther to the upper right in the twilight sky.

And from then on through the balance of this year, Venus will be purely a planet of the dawn.

Climax of Venus - Dramatic 'Inferior Conjunction'

SOURCE

Newfound Comet Lulin to Grace Night Skies



During the next few weeks, a comet bright enough for observation in binoculars and possibly even with the naked eye will provide a fine skywatching target when weather permits.

Comet Lulin will be closest to Earth on Feb. 24 and prime viewing will occur than and on surrounding nights. For sharp-eye viewers with dark, rural, skies, the comet is expected to be visible as a dim, fuzzy star.

People living in cities and suburbs are not expected to see the comet with the naked eye, but binoculars and telescopes will reveal its cloudy head and perhaps a striking tail, too. Comets are unpredictable, however, so it's impossible to say how bright this one might become.

Already Lulin is an enjoyable target for small telescopes, producing several striking photographs in the predawn sky. The object is best found using a sky map tailored to your location.

The discovery

The comet was photographed by Chi Sheng Lin using a 16-inch telescope at the Lulin Observatory at Nantou, Taiwan on July 11, 2007. But it was a 19-year old student, Quanzhi Ye at Sun Yat-sen University in Mainland China who first recognized the new object on three images that were taken by Lin.

Initially it was thought to be an asteroid, new images taken a week later revealed the telltale presence of a faint coma.

The discovery was part of the Lulin Sky Survey project to explore the various populations of small bodies in the solar system, especially objects that possibly could pose a hazard to the Earth. As such, the comet has been christened Comet Lulin, more formally known to astronomers as Comet C/2007 N3.

This comet is the brightest since the surprising outburst of Comet Holmes more than 15 months ago and in the coming weeks will become favorably placed in the evening sky. During mid-to-late February it will probably be about magnitude 5 or 6, making it perhaps visible to the naked eye in dark, rural locations and easily observable in binoculars or small telescopes.

Unusual orbit

Brian Marsden of the Smithsonian Astrophysical Observatory has calculated that Comet Lulin passed through the perihelion point of its orbit (its closest approach to the sun) on Jan. 10, 113 million miles (182 million kilometers) from the sun. However, while the comet is now receding from the sun, its distance from the Earth is decreasing, with a minimum of 38 million miles (61 million kilometers) on Feb. 24.

For this reason, the comet should be at its brightest during the last week of February; then it will fade fast by mid-March.

The orbit of Comet Lulin is very nearly a parabola, according to Marsden. It is also rather unusual since it is moving through space in a direction opposite to that of the planets at a very low inclination of just 1.6-degrees from the ecliptic. As such, because it is moving opposite to the motion of our Earth, the comet will appear to track rather quickly against the background stars as one observes the object from one night to the next.

In addition, over the next three weeks, the comet will appear to rise an average of about 20-minutes earlier each night. Right now, it is best seen in the predawn sky.

Rapid track

On the night of Feb. 7, for instance, Lulin will rise above the east-southeast horizon around midnight and will appear at its highest in the sky toward the south at the break of dawn. But on the night of the 24th, when it will be passing nearest to Earth, Lulin will be visible all night, rising in the east at dusk, peaking high in the south shortly after midnight and setting in the west around sunrise.

Currently located in the constellation Libra, Comet Lulin will appear to move on a northwest trajectory, crossing over into Virgo on Feb. 11 and passing 3-degrees north of the 1st-magnitude star Spica in Virgo on Feb. 16 (for comparison, your clenched fist held at arm's length measures about 10-degrees in width).

On the night of Feb. 23, now virtually at its peak brightness, the comet will be sitting just 2-degrees south-southwest of the planet Saturn, which you can use as a benchmark to locate the comet. Moreover, around this time, Comet Lulin will be racing at more than 5-degrees per day -- that's roughly the equivalent of the distance between the stars Dubhe and Merak, the "Pointer Stars" of the Big Dipper; so even a few minutes of watching with a telescope should reveal the comet's slow shift relative to background field stars.

On Feb. 27, the fading comet will slip just 1-degree south of the 1st-magnitude star, Regulus in Leo. And come the night of March 5, Lulin -- by then probably between magnitudes 6 and 7 and no longer visible without binoculars or a telescope -- will pass to within 2-degrees of the famous Beehive Star Cluster in Cancer.

Look for an Antitail

Comets are visible because radiation from the sun releases gas and dust from the comet. That material then shines with reflected sunlight, creating a cloudy head, or coma, and sometimes one or two tails.

Even when it's at its very brightest, naked-eye observers probably see Comet Lulin as resembling only a dim, fuzzy star. In binoculars, or a small telescope the comet may resemble an apple on a stick; that is, the comet's diffuse head or coma should appear round and somewhat condensed toward its center, with perhaps a tinge of blue or green, while a narrow tail of gas extends out to the northwest.

In addition, telescopic observers should also look for a "spike" of light, pointing in a direction opposite to the tail. This strange effect, called an "antitail," is caused by a thin sheet of dust that is expelled by the comet but normally is visible for a brief interval when the Earth passes through the comet's orbital plane.

But because Earth will remain in the comet's orbital plane through February and on into March, there will be an ongoing chance of catching a glimpse of the antitail as well.

SOURCE

Galactic Dust Bunnies Found to Contain Carbon After All

Using NASA's Spitzer Space Telescope, researchers have found evidence suggesting that stars rich in carbon complex molecules may form at the center of our Milky Way galaxy.

This discovery is significant because it adds to our knowledge of how stars form heavy elements -- like oxygen, carbon and iron -- and then blow them out across the universe, making it possible for life to develop.



Astronomers have long been baffled by a strange phenomenon: Why have their telescopes never detected carbon-rich stars at the center of our galaxy even though they have found these stars in other places? Now, by using Spitzer's powerful infrared detectors, a research team has found the elusive carbon stars in the galactic center.

"The dust surrounding the stars emits very strongly at infrared wavelengths," says Pedro García-Lario, a research team member who is on the faculty of the European Space Astronomy Center, the European Space Agency's center for space science. He co-authored a paper on this subject in the February 2009 issue of the journal Astronomy & Astrophysics.

"With the help of Spitzer spectra, we can easily determine whether the material returned by the stars to the interstellar medium is oxygen-rich or carbon-rich."

The team of scientists analyzed the light emitted from 40 planetary nebulae – blobs of dust and gas surrounding stars -- using Spitzer's infrared spectrograph. They analyzed 26 nebulae toward the center of the Milky Way -- a region called the "Galactic Bulge" -- and 14 nebulae in other parts of the galaxy. The scientists found a large amount of crystalline silicates and polycyclic aromatic hydrocarbons, two substances that indicate the presence of oxygen and carbon.

This combination is unusual. In the Milky Way, dust that combines both oxygen and carbon is rare and is usually only found surrounding a binary system of stars. The research team, however, found that the presence of the carbon-oxygen dust in the Galactic Bulge seems to be suggestive of a recent change of chemistry experienced by the star.

The scientists hypothesize that as the central star of a planetary nebula ages and dies, its heavier elements do not make their way to the star's outer layers, as they do in other stars. Only in the last moments of the central star's life, when it expands and then violently expels almost all of its remaining outer gasses, does the carbon become detectable. That's when astronomers see it in the nebula surrounding the star.

"The carbon produced through these recurrent 'thermal pulses' is very inefficiently dredged up to the surface of the star, contrary to what is observed in low-metallicity, galactic disk stars," said García-Lario. "It only becomes visible when the star is about to die." This study supports a hypothesis about why the carbon in some stars does not make its way to the stars' surfaces. Scientists believe that small stars -- those with masses up to one-and-a-half times that of our sun -- that contain lots of metal do not bring carbon to their surfaces as they age. Stars in the Galactic Bulge tend to have more metals than other stars, so the Spitzer data support this commonly held hypothesis. Before the Spitzer study, this hypothesis had never been supported by observation.

This aging and expelling process is typical of all stars. As stars age and die, they burn progressively heavier and heavier elements, beginning with hydrogen and ending with iron. Towards the end of their lives, some stars become what are called "red giants." These dying stars swell so large that if one of them were placed in our solar system, where the sun is now, its outermost border would touch Earth's orbit. As these stars pulsate – losing mass in the process – and then contract, they spew out almost all of their heavier elements. These elements are the building blocks of all planets, including our own Earth (as well as of human beings and any other life forms that may exist in the universe).

The paper is co-authored by José Vicente Perea-Calderón of the European Space Astronomy Center in Villanueva de la Cañada, Spain; Domingo Anibal García-Hernández of the Instituto de Astrofísica de Canarias, on Spain's Tenerife island; Ryszard Szczerba of the Nicolaus Copernicus Astronomical Center in Torun, Poland; and Matt Bobrowsky of the University of Maryland, College Park.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

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Mars Google Logo for Giovanni Schiaparelli's Birthday



Google celebrates Giovanni Schiaparelli's Birthday but links to Google Earth and not a search term for a change.

Who is Giovanni Schiaparelli? Wiki Says...

Giovanni Virginio Schiaparelli (March 14, 1835 – July 4, 1910) was an Italian astronomer and science historian. He studied at the University of Turin and Berlin Observatory and worked for over forty years at Brera Observatory.

He was also a senator of the Kingdom of Italy, a member of the Accademia dei Lincei, the Accademia delle Scienze di Torino and the Regio Istituto Lombardo, and is particularly known for his studies of Mars.

Mars

Among Schiaparelli's contributions are his telescopic observations of Mars. In his initial observations, he named the "seas" and "continents" of Mars.

During Italy's "Great Opposition" of 1877, he observed a dense network of linear structures on the surface of Mars which he called "canali" in Italian, meaning "channels" but mistranslated as "canals". While the latter term indicates an artificial construction, the former indicates the connotation that it can also be a natural configuration of the land.

From this incorrect translation, various assumptions about life on Mars derived, as the "canals" of Mars soon became famous, giving rise to waves of hypotheses, speculation and folklore about the possibility of life on Mars.

Among the most fervent supporters of the artificial canals was the famous American astronomer Percival Lowell who spent much of his life trying to prove the existence of intelligent life on the red planet. Later, however, with notable thanks to the observations of Italian astronomer Vicenzo Cerulli, scientists ascertained that the famous channels were actually mere optical illusions

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Kepler telescope to soon begin operating
PASADENA, Calif. (UPI) -- U.S. space agency engineers say they have ejected the dust cover from the Kepler space telescope, which is designed to search for worlds similar to Earth.

"The cover released and flew away exactly as we designed it to do," said Kepler Project Manager James Fanson of the National Aeronautics and Space Administration's Jet Propulsion Laboratory. "This is a critical step toward answering a question that has come down to us across 100 generations of human history -- are there other planets like Earth or are we alone in the galaxy?"

The space telescope was launched March 6 from Cape Canaveral, Fla. It will spend 3 1/2 years searching more than 100,000 stars in the Milky Way galaxy for signs of Earth-size planets. Some of the planets are expected to orbit in a star's "habitable zone" -- a warm region where water could pool on a planet's surface.

Kepler's oval-shaped dust cover, measuring 67 inches by 52 inches, protected the instrument from contamination before and after launch.

NASA said the space telescope will undergo calibration for several weeks, after which science observations will begin.


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