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Alaskan Bird Deformities Are Puzzling, Creepy
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Alaskan Bird Deformities Are Puzzling, Creepy
By Brandon Keim
November 9, 2010 |
1:38 pm |
Categories: Animals, Environment
In a possible symptom of environmental decline, Alaska’s birds have experienced a sudden and inexplicable rash of beak deformities.
About one in 16 crows and black-capped chickadees suffer from a condition called avian keratin disorder, which causes their beaks to become morbidly elongated and crossed.
Rates of the debilitating disorder are 10 times higher than usual. That’s higher than has ever been recorded in any wild-bird population, and most of this rise happened over the last decade. Dozens of other bird species are afflicted. Nobody knows why, but it’s probably not a good sign.
“The sudden appearance of a large cluster of animals with gross abnormalities may signal a significant change in an ecosystem,” wrote U.S. government biologists Colleen Handel and Kimberly Trust in paper published in October in The Auk.
Many possible culprits have been identified. One is environmental contamination; toxins and heavy metals have caused past beak-deformity epidemics in the Great Lakes and California. But those outbreaks occurred in clusters, while Alaska’s deformities are widespread and affect species living in different habitats, with different diets.
Bacteria, viruses, fungi or nutritional deficiencies could be responsible, wrote the researchers. More tests will be run. All that’s clear now is that something is going wrong.
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Milky Way May Fizzle Out Sooner Than Expected
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Milky Way May Fizzle Out Sooner Than Expected
By Dave Mosher
November 9, 2010 |
2:21 pm |
Categories: Astronomy, Space
A thick bar of stars, gas and dust spanning across the Milky Way’s center could be speeding star formation and, as supplies run out, our host galaxy’s eventual death.
A new study, the first to trickle out of Galaxy Zoo’s second crowd-sourced scientific effort, buoys the idea that bars somehow encourage galaxies to form big, blue and short-lived stars, as well as funnel gas and dust to supermassive black holes lurking at their cores. In the process, bars may quickly consume star-making materials to leave behind only a “dead” galaxy of red and fading stars.
“Basically, as you go from the really youthful galaxies to the dead ones, more and more frequently we see bars in them,” said Kevin Schawinski, an astronomer at Yale University and co-author of the study, set to appear in an upcoming edition of the Monthly Notices of the Royal Astronomical Society. “Our immediate suspicion is that bars are involved in speeding galaxy evolution.”
Schawinski said the work isn’t proof that bars shorten galaxies’ star-forming lifespans — it could be the other way around, with bars being a product of dying galaxies. But he said the data backs the first idea, which is shared among many astronomers.
“Bars seem to help exhaust supplies of gas, pushing galaxies to a passive state and no longer forming any stars. This is inline with our results and what others are saying,” Schawinski said. “The Milky Way, which is more or less agreed to be a barred spiral, may be an example of a galaxy in transition from an active state to something anemic and passive.”
George Djorgovski, an astronomer at Caltech who described his team as “in a friendly competition of sorts” with Galaxy Zoo, said the new research is interesting and does support existing ideas in the field.
“More than anything it illustrates how citizen science approach can be used very effectively, both in research and outreach,” Djorgovski said. “It’s a pretty exciting way of doing science, and Galaxy Zoo is certainly the most successful to date.”
Launched in July 2007, Galaxy Zoo enlisted the help of web citizens to classify a million galaxies photographed by the Sloan Digital Sky Survey, or SDSS. The effort produced at least 15 published studies, with more under review.
During the second phase from February 2009 through April 2010, called Galaxy Zoo 2, volunteers analyzed a quarter million of the brightest, previously classified disk-shaped galaxies in more detail. In all, 200,000 volunteers made 60 million classifications, or about 240 assessments per galaxy. Each object is between 140 million and 875 million light-years away.
“Our volunteers essentially became the world’s biggest and best pattern-recognizing supercomputer,” Schawinski said. “They were able to measure something that’s very, very hard to teach a computer, which is to recognize bars and other details in [astronomical images].”
Of 13,665 disk-shaped galaxies, Galaxy Zoo 2 discovered about 30 percent of them have bars. What’s more, 10 to 20 percent of the blue star-forming galaxies have bars, while about 50 percent of passive reddish galaxies have them. In contrast, Schawinski said only about 6 percent of non-barred galaxies are “red and dead.”
“Stars of all colors are being born at the same time, but blue stars are the ones that die very quickly. If star formation stops, all you have are red stars.” Schawinski said, adding that football-shaped elliptical galaxies don’t have great mechanisms to churn star formation, leaving most of them red-and-dead. “Spiral galaxies, on the other hand, still have a lot of gas in their disks, and stars are being born in them all of the time, including in our Milky Way,” he said.
If spiral galaxies are left to their own demise, Djorgovski said it takes a few billion years for star formation to fizzle out (the process consumes 99.9 percent gas and dust supplies, black holes just a shred at 0.01 percent). Yet many such galaxies have lasted longer than that, especially those similar to the Milky Way.
“Galaxies keep accreting fresh gas from space as they move through it, otherwise they would have run out long ago,” Djorgovski said, adding that many galaxies have corralled hundreds of billions of stars for about 10 billion years. “There’s still plenty of gas out there.”
When the Milky Way does run out of available stellar fuel and succumbs to its reddish death, which is extremely difficult to precisely predict, all may not be lost. The nearby Andromeda galaxy is expected to collide with our galaxy in about 4.5 billion years.
“When the Andromeda galaxy collides and merges with the Milky Way, it’s going to be spectacular fireworks of star formation,” Schawinski said, noting how gravity-induced chaos should stir up diffuse gas and dust. “Maybe even the galaxies’ black holes will start feeding again, too.”
Images: 1) Astronomers’ best guess of what the Milky Way galaxy looks like from above. NASA/JPL-Caltech (hi-res). 3) Images Galaxy Zoo 2 volunteers classified. Top: A red barred spiral galaxy. Bottom: A blue spiral galaxy with no bar. Galaxy Zoo/SDSS. 2) The barred spiral galaxy NGC 1300. NASA/ESA/Hubble Heritage (hi-res).
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Gamma-RayvBubbles of Energy Are Found in Galaxy
From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or about half of the Milky Way’s diameter, as shown in this illustration.
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Bubbles of Energy Are Found in Galaxy
From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or about half of the Milky Way’s diameter, as shown in this illustration.
By DENNIS OVERBYE
Something big is going on at the center of the galaxy, and astronomers are happy to say they don’t know what it is.
A group of scientists working with data from NASA’s Fermi Gamma-Ray Space Telescope said Tuesday that they had discovered two bubbles of energy erupting from the center of the Milky Way galaxy. The bubbles, they said at a news conference and in a paper to be published Wednesday in The Astrophysical Journal, extend 25,000 light years up and down from each side of the galaxy and contain the energy equivalent to 100,000 supernova explosions.
“They’re big,” said Doug Finkbeiner of the Harvard-Smithsonian Center for Astrophysics, leader of the team that discovered them.
The source of the bubbles is a mystery. One possibility is that they are fueled by a wave of star births and deaths at the center of the galaxy. Another option is a gigantic belch from the black hole known to reside, like Jabba the Hutt, at the center of the Milky Way. What it is apparently not is dark matter, the mysterious something that astronomers say makes up a quarter of the universe and holds galaxies together.
“Wow,” said David Spergel, an astrophysicist at Princeton who was not involved in the work.
“And we think we know a lot about our own galaxy,” Dr. Spergel added, noting that the bubbles were almost as big as the galaxy and yet unsuspected until now.
Jon Morse, head of astrophysics at NASA headquarters, said, “This shows again that the universe is full of surprises.”
One of the most surprised was Dr. Finkbeiner. A year ago he was part of a group led by Gregory Dobler of the Kavli Institute for Theoretical Physics in Santa Barbara, Calif., that said it had discerned the existence of a mysterious fog of high-energy particles buzzing around the center of the Milky Way. The particles manifested themselves as a haze of extra energy after all the known sources of gamma rays — the most energetic form of electromagnetic radiation — had been subtracted from Fermi data that had recently been made public.
At the time, Dr. Finkbeiner and his colleagues speculated that the haze was produced by dark matter. The center of the galaxy is home to all manner of wild and woolly high-energy phenomena, including a gigantic black hole and violently spinning pulsars, but cosmological theories also suggest that dark matter would be concentrated there. Collisions of dark matter particles, the theory goes, could produce showers of gamma rays.
But in the follow-up analysis, the haze — besides being bigger than Dr. Finkbeiner and his colleagues had thought — turned out to have sharp boundaries, like, well, a bubble. Dark matter, according to the prevailing theory, should be more diffuse.
“Dark matter has been there billions of years,” Dr. Finkbeiner explained. “If something has been going on for billions of years, you wouldn’t expect a sharp edge.”
Read more at www.nytimes.com
He and the other scientists said this did not mean that dark matter was not there clogging the center of the galaxy, but that it would be harder to see.
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Galactic Core Spews Weird Radiation Bubbles
Two colossal bubbles of high-energy radiation are careening out of the Milky Way’s core, a new analysis of images from NASA’s Fermi gamma-ray space telescope shows.
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Galactic Core Spews Weird Radiation Bubbles
By Dave Mosher
November 9, 2010 |
5:31 pm |
Categories: Astronomy, Space
Two colossal bubbles of high-energy radiation are careening out of the Milky Way’s core, a new analysis of images from NASA’s Fermi gamma-ray space telescope shows.
The 19 months’ worth of data reveal twin 25,000-light-year-long blobs of gamma-ray and X-ray radiation are poking out above and below our galaxy’s 100,000-light-year-long disk of stars.
“We don’t fully understand their nature or origin,” astronomer Doug Finkbeiner of Harvard University said in a press release Nov. 9.
One prime suspect for the bubbles’ creator is the supermassive black hole at the center of the galaxy, according to the study, published on arXiv.org and accepted to The Astrophysical Journal. Weighing in at more than 4 million times the mass of the sun, such a black hole is capable of furious outbursts of energy when surrounding matter falls into it.
“Another possible source of dramatic energy injection is a powerful starburst in the nucleus,” Finkbeiner and other authors wrote in the study. Such a starburst is “driven by the energy released by supernova explosions and stellar winds following an intense episode of star formation,” they wrote, and may have occurred some 10 million years ago.
Whatever is blowing the bubbles from the Milky Way’s core, the authors suspect new instruments, including the Planck spacecraft (launched in 2009) and the eROSITA X-ray telescope (scheduled to launch in 2012), will find out.
Images: 1) In this illustration, gamma-ray bubbles (purple) flanked by X-rays (blue) protrude 25,000 light-years each out of the Milky Way. NASA Goddard (hi-res). 2) The gamma-ray sky, as seen by NASA’s Fermi space telescope. A dumbbell-shaped feature (yellow/orange) can be seen at galactic center extending out of the Milky Way’s flat plane. NASA/DOE/Fermi LAT/D. Finkbeiner et al. (hi-res)Read more at www.wired.com
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