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Title: The Death Star
Source:
London Telegraph
URL Source: http://www.telegraph.co.uk/news/mai ... l=/news/2006/08/31/wstar31.xml
Published: Aug 31, 2006
Author: Roger Highfield
Post Date: 2006-08-31 20:41:52 by Peetie Wheatstraw
Keywords: None
Views: 81
Comments: 2
For the first time a star has been observed in real time as it dies and becomes a supernova — an immensely powerful explosion. The cataclysmic supernova, briefly outshining the Milky Way galaxy, occurred 440 million light years away in a star-forming galaxy in the constellation of Aries. Large stars are likely to end their days in this way, by blowing themselves to smithereens. Aftermaths of supernovae have been observed many times but scientists have never before seen one of the explosions happening. They will now have an unprecedented view of a supernova from start to finish across many wavelengths, including radio and X-ray. Radio telescopes have seen the burst from the day it was detected — another first. In a few hundred years the supernova may resemble the wispy remnants of Cassiopeia A. The event, described today in the journal Nature, began on Feb 18 with a gamma ray burst (GRB), an unimaginably powerful outpouring of gamma or X-rays. Astronomers realised that it was an unusual event because it was 25 times closer and 100 times longer than typical. The burst, called GRB 060218 after the date it was discovered, lasted almost 40 minutes, rather than the more usual few thousandths of a second to tens of seconds. The exceptionally long burst, in the form of a jet of high-energy X-rays, pierced through the doomed star from its core and sent out a warning within minutes that a supernova was imminent. As the gamma rays faded away, the massive star exploded. Three telescopes on board Nasa's Swift satellite captured the whole sequence. A team member, Paul O'Brien, from Leicester University, said: "The results suggest that a broad jet expanded into the surroundings but it was accompanied by a slower-moving two million degree bubble of gas produced from the shock wave of the exploding star. This is the first time such an extraordinary event has been seen from a GRB." The star's explosive power is equivalent to 100,000,000, 000, 000, 000, 000, 000, 000,000,000 tons of TNT, or to giving off in half an hour as much energy as our Sun radiates in about a billion years. John Nousek, Swift's mission director at Penn State University, Pennsylvania, said: "There are still many unknowns. This could be a new kind of burst, or we may be seeing a gamma-ray burst from an entirely different angle. This off-angle glance has given us an entirely new approach to studying star explosions." Swift's telescopes are designed to cover gamma-ray, X-ray, ultraviolet and optical wavelengths of light. X-rays were seen to fade to ultraviolet then to the optical range. Two days after the initial explosion, the star had become a classic supernova, a glowing cloud of gas powered by the decay of radioactive debris. Prof Keith Mason, Britain's lead investigator for the ultraviolet/optical telescope on Swift, said: "Usually these events are not detected until after the supernova has brightened substantially in the optical wavelength, many days after the explosion. "On this occasion we were able to study the remarkable event in all its glory from the very beginning." Andrew Levan, of Hertfordshire University, said: "As well as studying the early evolution of the supernova for the first time, these observations show how the material ejected in the explosion evolves in the following days and weeks."
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#1. To: All (#0)
Death Star, Before and After:
Republicans were running things there...
the law, in its majestic equality, forbids the rich as well as the poor to sleep under bridges, beg in the streets and steal bread.
#2. To: Peetie Wheatstraw (#0)
The event, described today in the journal Nature, began on Feb 18 with a gamma ray burst (GRB), an unimaginably powerful outpouring of gamma or X-rays. Astronomers realised that it was an unusual event because it was 25 times closer and 100 times longer than typical.
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