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Saturday, January 12, 2013 4:31:04 AM
Largest Spiral Galaxy in Universe Revealed
This composite of the spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory's Very Large Telescope with far-ultraviolet data from NASA's GALEX and infrared data acquired by NASA's Spitzer Space Telescope. The spiral is 522,000 light-years across from armtip to armtip, which makes NGC 6872 about 5 times the size of the Milky Way.
CREDIT: NASA's Goddard Space Flight Center/ESO/JPL-Caltech/DSS
by Mike Wall, SPACE.com Senior Writer
Date: 10 January 2013 Time: 04:58 PM ET
Astronomers have crowned the universe's largest known spiral galaxy, a spectacular behemoth five times bigger than our own Milky Way.
The title-holder is now NGC 6872, a barred spiral found 212 million light-years away in the southern constellation Pavo, researchers announced today (Jan. 10). The distance between NGC 6872's two huge spiral arms is 522,000 light-years, compared to about 100,000 light-years for the Milky Way [ http://www.space.com/14249-milkyway-galaxy-photos.html ].
NGC 6872 has ranked among the largest known spiral galaxies for decades. But it has only now been crowned champion, after detailed study of data gathered by a number of instruments, including NASA's Galaxy Evolution Explorer spacecraft [ http://www.space.com/15723-nasa-loans-galex-space-telescope-caltech.html ], or GALEX.
"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system," lead scientist Rafael Eufrasio, of NASA's Goddard Space Flight Center in Greenbelt, Md., and the Catholic University of America, said in a statement. [Photos: 65 All-Time Great Galaxy Hits [ http://www.space.com/13262-65-great-galaxy-photos-space-images.html ]]
Eufrasio presented the results today at the 221st meeting of the American Astronomical Society [ http://www.space.com/19128-american-astronomical-society-221st-meeting.html ] in Long Beach, Calif. He stressed that spirals bigger than NGC 6872 may be out there, still waiting to be spotted and studied in depth.
NCG 6872's enormous size and odd appearance are the consequence of its gravitational interaction with a neighbor galaxy called IC 4970, which contains just 20 percent of NGC 6872's mass, researchers said.
Computer simulations suggest that IC 4970 made its closest approach about 130 million years ago, stirring up a burst of activity in certain parts of NCG 6872.
"The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems," Duilia de Mello, a professor of astronomy at Catholic University, said in a statement.
NGC 6872's bar, which links the galaxy's arms and its central regions, is also huge. With a radius of 26,000 light-years, it's about twice as big as the bars of nearby spirals, researchers said. No evidence of recent star formation is apparent in NGC 6872's bar, suggesting that it formed several billion years ago or more.
The $150 million GALEX mission launched in April 2003 to study the history of star formation in the universe. NASA stopped funding the mission in February 2011, and in May 2012 it handed the spacecraft's reins over to the California Institute of Technology, which is keeping the mission going with private funds.
Copyright © 2013 TechMediaNetwork.com
http://www.space.com/19222-largest-spiral-galaxy-universe.html [with comments] [ http://www.jpl.nasa.gov/news/news.php?release=2013-016&rn=news.xml&rst=3651 ; http://www.nasa.gov/mission_pages/galex/galex20130110.html ]
===
Largest Structure in Universe Discovered
Artist's rendering of a quasar, a very energetic and brilliant black-hole-powered galactic nucleus. Quasars first appeared in the very early universe, soon after the Big Bang.
CREDIT: ESO/M. Kornmesser
[ http://www.space.com/19227-biggest-structure-universe-explained-infographic.html ]
by Mike Wall, SPACE.com Senior Writer
Date: 11 January 2013 Time: 04:01 AM ET
Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretches 4 billion light-years from end to end.
The structure is a large quasar group (LQG), a collection of extremely luminous galactic nuclei powered by supermassive central black holes [ http://www.space.com/18668-biggest-black-hole-discovery.html ]. This particular group is so large that it challenges modern cosmological theory, researchers said.
"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," lead author Roger Clowes, of the University of Central Lancashire in England, said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe [ http://www.space.com/13336-universe-history-structure-evolution-infographic.html ]."
Quasars [ http://www.space.com/17262-quasar-definition.html ] are the brightest objects in the universe. For decades, astronomers have known that they tend to assemble in huge groups, some of which are more than 600 million light-years wide.
But the record-breaking quasar group, which Clowes and his team spotted in data gathered by the Sloan Digital Sky Survey, is on another scale altogether. The newfound LQC is composed of 73 quasars and spans about 1.6 billion light-years in most directions, though it is 4 billion light-years across at its widest point.
To put that mind-boggling size into perspective, the disk of the Milky Way galaxy — home of Earth's solar system — is about 100,000 light-years wide. And the Milky Way is separated from its nearest galactic neighbor, Andromeda, by about 2.5 million light-years.
The newly discovered LQC is so enormous, in fact, that theory predicts it shouldn't exist, researchers said. The quasar group appears to violate a widely accepted assumption known as the cosmological principle, which holds that the universe is essentially homogeneous when viewed at a sufficiently large scale.
Calculations suggest that structures larger than about 1.2 billion light-years should not exist, researchers said.
"Our team has been looking at similar cases which add further weight to this challenge, and we will be continuing to investigate these fascinating phenomena," Clowes said.
The new study [abstract http://mnras.oxfordjournals.org/content/early/2013/01/07/mnras.sts497.short , full http://mnras.oxfordjournals.org/content/early/2013/01/07/mnras.sts497.full ] was published today (Jan. 11) in the Monthly Notices of the Royal Astronomical Society [ http://mnras.oxfordjournals.org/ ].
Copyright © 2013 TechMediaNetwork.com
http://www.space.com/19220-universe-largest-structure-discovered.html [with comments]
===
Cosmic 'Bullets' Slam Orion Nebula in Dazzling Photo
This image, obtained during the late commissioning phase of the GeMS adaptive optics system, with the Gemini South AO Imager (GSAOI) on the night of December 28, 2012, reveals exquisite details in the outskirts of the Orion Nebula.
CREDIT: Gemini Observatory/AURA
11 January 2013
http://www.space.com/19203-orion-nebula-supersonic-bullets-photo.html [with comments]
===
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This composite of the spiral galaxy NGC 6872 combines visible light images from the European Southern Observatory's Very Large Telescope with far-ultraviolet data from NASA's GALEX and infrared data acquired by NASA's Spitzer Space Telescope. The spiral is 522,000 light-years across from armtip to armtip, which makes NGC 6872 about 5 times the size of the Milky Way.
CREDIT: NASA's Goddard Space Flight Center/ESO/JPL-Caltech/DSS
by Mike Wall, SPACE.com Senior Writer
Date: 10 January 2013 Time: 04:58 PM ET
Astronomers have crowned the universe's largest known spiral galaxy, a spectacular behemoth five times bigger than our own Milky Way.
The title-holder is now NGC 6872, a barred spiral found 212 million light-years away in the southern constellation Pavo, researchers announced today (Jan. 10). The distance between NGC 6872's two huge spiral arms is 522,000 light-years, compared to about 100,000 light-years for the Milky Way [ http://www.space.com/14249-milkyway-galaxy-photos.html ].
NGC 6872 has ranked among the largest known spiral galaxies for decades. But it has only now been crowned champion, after detailed study of data gathered by a number of instruments, including NASA's Galaxy Evolution Explorer spacecraft [ http://www.space.com/15723-nasa-loans-galex-space-telescope-caltech.html ], or GALEX.
"Without GALEX's ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system," lead scientist Rafael Eufrasio, of NASA's Goddard Space Flight Center in Greenbelt, Md., and the Catholic University of America, said in a statement. [Photos: 65 All-Time Great Galaxy Hits [ http://www.space.com/13262-65-great-galaxy-photos-space-images.html ]]
Eufrasio presented the results today at the 221st meeting of the American Astronomical Society [ http://www.space.com/19128-american-astronomical-society-221st-meeting.html ] in Long Beach, Calif. He stressed that spirals bigger than NGC 6872 may be out there, still waiting to be spotted and studied in depth.
NCG 6872's enormous size and odd appearance are the consequence of its gravitational interaction with a neighbor galaxy called IC 4970, which contains just 20 percent of NGC 6872's mass, researchers said.
Computer simulations suggest that IC 4970 made its closest approach about 130 million years ago, stirring up a burst of activity in certain parts of NCG 6872.
"The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems," Duilia de Mello, a professor of astronomy at Catholic University, said in a statement.
NGC 6872's bar, which links the galaxy's arms and its central regions, is also huge. With a radius of 26,000 light-years, it's about twice as big as the bars of nearby spirals, researchers said. No evidence of recent star formation is apparent in NGC 6872's bar, suggesting that it formed several billion years ago or more.
The $150 million GALEX mission launched in April 2003 to study the history of star formation in the universe. NASA stopped funding the mission in February 2011, and in May 2012 it handed the spacecraft's reins over to the California Institute of Technology, which is keeping the mission going with private funds.
Copyright © 2013 TechMediaNetwork.com
http://www.space.com/19222-largest-spiral-galaxy-universe.html [with comments] [ http://www.jpl.nasa.gov/news/news.php?release=2013-016&rn=news.xml&rst=3651 ; http://www.nasa.gov/mission_pages/galex/galex20130110.html ]
===
Largest Structure in Universe Discovered
Artist's rendering of a quasar, a very energetic and brilliant black-hole-powered galactic nucleus. Quasars first appeared in the very early universe, soon after the Big Bang.
CREDIT: ESO/M. Kornmesser
[ http://www.space.com/19227-biggest-structure-universe-explained-infographic.html ]
by Mike Wall, SPACE.com Senior Writer
Date: 11 January 2013 Time: 04:01 AM ET
Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretches 4 billion light-years from end to end.
The structure is a large quasar group (LQG), a collection of extremely luminous galactic nuclei powered by supermassive central black holes [ http://www.space.com/18668-biggest-black-hole-discovery.html ]. This particular group is so large that it challenges modern cosmological theory, researchers said.
"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," lead author Roger Clowes, of the University of Central Lancashire in England, said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe [ http://www.space.com/13336-universe-history-structure-evolution-infographic.html ]."
Quasars [ http://www.space.com/17262-quasar-definition.html ] are the brightest objects in the universe. For decades, astronomers have known that they tend to assemble in huge groups, some of which are more than 600 million light-years wide.
But the record-breaking quasar group, which Clowes and his team spotted in data gathered by the Sloan Digital Sky Survey, is on another scale altogether. The newfound LQC is composed of 73 quasars and spans about 1.6 billion light-years in most directions, though it is 4 billion light-years across at its widest point.
To put that mind-boggling size into perspective, the disk of the Milky Way galaxy — home of Earth's solar system — is about 100,000 light-years wide. And the Milky Way is separated from its nearest galactic neighbor, Andromeda, by about 2.5 million light-years.
The newly discovered LQC is so enormous, in fact, that theory predicts it shouldn't exist, researchers said. The quasar group appears to violate a widely accepted assumption known as the cosmological principle, which holds that the universe is essentially homogeneous when viewed at a sufficiently large scale.
Calculations suggest that structures larger than about 1.2 billion light-years should not exist, researchers said.
"Our team has been looking at similar cases which add further weight to this challenge, and we will be continuing to investigate these fascinating phenomena," Clowes said.
The new study [abstract http://mnras.oxfordjournals.org/content/early/2013/01/07/mnras.sts497.short , full http://mnras.oxfordjournals.org/content/early/2013/01/07/mnras.sts497.full ] was published today (Jan. 11) in the Monthly Notices of the Royal Astronomical Society [ http://mnras.oxfordjournals.org/ ].
Copyright © 2013 TechMediaNetwork.com
http://www.space.com/19220-universe-largest-structure-discovered.html [with comments]
===
Cosmic 'Bullets' Slam Orion Nebula in Dazzling Photo
This image, obtained during the late commissioning phase of the GeMS adaptive optics system, with the Gemini South AO Imager (GSAOI) on the night of December 28, 2012, reveals exquisite details in the outskirts of the Orion Nebula.
CREDIT: Gemini Observatory/AURA
11 January 2013
http://www.space.com/19203-orion-nebula-supersonic-bullets-photo.html [with comments]
===
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