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cyrus Site Admin
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cyrus Site Admin
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Posted: Mon May 07, 2007 8:46 pm Post subject: NASA's Chandra Sees Brightest Supernova Ever |
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NASA's Chandra Sees Brightest Supernova Ever
By: NASA
Published: May 7, 2007 at 07:17
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http://www.yubanet.com/artman/publish/article_56449.shtml
The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy.
According to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes, the supernova SN 2006gy is the brightest and most energetic stellar explosion ever recorded and may be a long-sought new type of explosion. The top panel of this graphic is an artist's illustration that shows what SN 2006gy may have looked like if viewed at a close distance. The bottom left panel is an infrared image, using adaptive optics at the Lick Observatory, of NGC 1260, the galaxy containing SN 2006gy. The panel to the right shows Chandra's X-ray image of the same field of view, again showing the nucleus of NGC 1260 and SN 2006gy. Image credit: X-ray: NASA/CXC/UC Berkeley/N.Smith et al.; IR: Lick/UC Berkeley/J.Bloom & C.Hansen
"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before."
Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died. It is unprecedented, however, to find such a massive star and witness its death. The discovery of the supernova, known as SN 2006gy, provides evidence that the death of such massive stars is fundamentally different from theoretical predictions.
"Of all exploding stars ever observed, this was the king," said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. "We were astonished to see how bright it got, and how long it lasted."
The Chandra observation allowed the team to rule out the most likely alternative explanation for the supernova: that a white dwarf star with a mass only slightly higher than the sun exploded into a dense, hydrogen-rich environment. In that event, SN 2006gy should have been 1,000 times brighter in X-rays than what Chandra detected.
"This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star," said Dave Pooley of the University of California at Berkeley, who led the Chandra observations.
The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding. This large mass loss is similar to that seen from Eta Carinae, a massive star in our galaxy, raising suspicion that Eta Carinae may be poised to explode as a supernova. Although SN 2006gy is intrinsically the brightest supernova ever, it is in the galaxy NGC 1260, some 240 million light years away. However, Eta Carinae is only about 7,500 light years away in our own Milky Way galaxy.
"We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," said Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research. "Eta Carinae's explosion could be the best star-show in the history of modern civilization."
Supernovas usually occur when massive stars exhaust their fuel and collapse under their own gravity. In the case of SN 2006gy, astronomers think that a very different effect may have triggered the explosion. Under some conditions, the core of a massive star produces so much gamma ray radiation that some of the energy from the radiation converts into particle and anti-particle pairs. The resulting drop in energy causes the star to collapse under its own huge gravity.
After this violent collapse, runaway thermonuclear reactions ensue and the star explodes, spewing the remains into space. The SN 2006gy data suggest that spectacular supernovas from the first stars - rather than completely collapsing to a black hole as theorized - may be more common than previously believed.
"In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole."
The results from Smith and his colleagues will appear in The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. |
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cyrus Site Admin
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Posted: Tue May 08, 2007 9:53 am Post subject: Nasa sees brightest supernova |
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Nasa sees brightest supernova
James Randerson
Tuesday May 8, 2007
Guardian Unlimited
Source: http://www.guardian.co.uk/space/article/0,,2074918,00.html
A Nasa illustration shows what the supernova may have looked like. Photograph: AP/Nasa/Chandra x-ray centre/M Weiss
The brightest supernova ever seen has been observed by Nasa's orbiting Chandra x-ray telescope.
The huge stellar explosion released around 100 times more energy than a typical supernova and was 100 million billion times brighter than the sun at its peak.
It is very unusual to observe the death of a super-massive star, so scientists will be keen to use the data from the orbiting telescope and others on the ground to piece together what happened.
"We understand rather little about the most massive stars in the universe," said Jane Drew an astrophysicist at Imperial College London "They are very rare so we get our hands on them not very often. It's a bit like always getting to the crime scene after the criminal has gone and getting the catastrophe that is left behind."
She said super-massive stars had a "live fast, die young" existence, in astronomical terms. They typically burn for just 1m years, while our sun has been in existence for more than 4.5 bn.
"We know that they live short and very furious lives," she said, "They almost switch on and then, bang, they are gone." The star that gave rise to the explosion was around 150 times more massive than our own sun.
Usually, supernovae occur when stars exhaust their fuel and collapse. But astonomers think the SN 2006gy supernova was different. Its massive core may have produced so much gamma radiation that some of the energy was converted into particle and anti-particle pairs.
This would have produced a massive gravitational pull, tugging the star in on itself and triggering runaway thermonuclear reactions that caused the massive explosion, which spewed detritus into space.
Similar acts of massive cosmic littering have been vital for the development of the universe as we know it and, crucially for life. Stars are factories that produce heavier elements, such as iron, so life could not exist without them.
"Of all exploding stars ever observed, this was the king," said Alex Filippenko, leader of ground-based observations at the Keck observatory in Mauna Kea, Hawaii, and the Lick observatory at Mount Hamilton, California. "We were astonished to see how bright it got and how long it lasted."
"This was a truly monstrous explosion, 100 times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team. "That means the star that exploded might have been as massive as a star can get - about 150 times [the size of] our sun. We've never seen that before."
SN 2006gy will not trouble us too much because the galaxy it is in - called NGC 1260 - is 240m light years away. However, closer to home, in the Milky Way, is a star called Eta Carinae, a mere 7,500 light years or so away. This has been losing mass rapidly and looks like it might go supernova. It is hard to predict what the event would look like to us, but some suggest it would be so bright that it would be visible alongside the sun during the day.
"We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," said Mario Livio of the Space Telescope Science Institute, Baltimore. "Eta Carinae's explosion could be the best star show in the history of modern civilisation." |
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cyrus Site Admin
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Posted: Fri May 18, 2007 2:24 pm Post subject: Solar System |
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![](http://www.solarviews.com/raw/misc/ss2b.jpg) |
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cyrus Site Admin
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Posted: Fri May 18, 2007 2:45 pm Post subject: Now how big are we? |
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Now How Big Are We When Sun Become Just A Pixel In the Big Picture?
And, how big are the things that will upset us today?
Or, for that matter, the things that are important?
We Should KEEP LIFE IN PERSPECTIVE With Better Vision and Mission ....
Source: http://elronsviewfromtheedge.wordpress.com/2006/07/13/feeling-insignificant-yet/
Now How Big Are We When Sun Become Just A Pixel In the Big Picture? Are We Feeling insignificant yet?
Human Being Might Become Significant If and When We Have Correct PERSPECTIVE, VISION, MISSION ...
The perspective we get on Earth, our planet appears to be big and sturdy with an endless ocean of air. From space, astronauts often get the impression that the Earth is small with a thin, fragile layer of atmosphere. For a space traveler, the distinguishing Earth features are the blue waters, brown and green land masses and white clouds set against a black background. We should love and respect our small beautiful mother earth planet.
Many dream of traveling in space and viewing the wonders of the universe. In reality all of us are space travelers. Our spaceship is the planet Earth, traveling at the speed of 108,000 kilometers (67,000 miles) an hour. In order to control unlimited human greed and power in this century we must educate ourselves that as long as human being can not create self sufficient spaceship like earth then we must be wise how we use the earth resources and human being is not the only owner of this spaceship..... |
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