laogaiguk
Joined: 06 Dec 2005
Location: somewhere in Korea
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 Posted: Thu Sep 21, 2006 8:42 pm Post subject: Experts rethinking how stars explode |
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Experts rethinking how stars explode
POSTED: 10:32 a.m. EDT, September 21, 2006
WASHINGTON (Reuters) -- Astronomers have discovered a distant supernova, or exploded star, so large that it will force scientists to question their understanding of how certain older stars disintegrate.
Scientists have believed that dying stars known as "white dwarfs" can't expand to more than 1.4 times the size of our sun without exploding in a massive thermonuclear blast.
That rule, known as the "Chandrasekhar Limit," has served as the foundation of decades of astrophysical research and helped scientists estimate the size of the universe.
But a team of astronomers said on Wednesday that they have found a supernova in a galaxy 4 billion light years away that reached a mass twice that of the sun before exploding.
"It should not be possible to break this limit but nature has found a way," said Andy Howell, the University of Toronto researcher who discovered the supernova.
"Now we have to figure out how nature did it," Howell said in a statement.
The star could have been spinning so fast that centrifugal force pushed it beyond the usual limit, Howell and other researchers said. The explosion also could have come from two white-dwarf stars merging.
White dwarfs typically explode into supernovas after pulling gases from a nearby star. Because they give off a consistent light, these supernovas can serve as markers that help measure the universe.
Scientists relied on them to discover in 1998 that the universe is expanding at an accelerating rate.
The new supernova doesn't necessarily undermine that discovery or other previous research, the astronomers said. But scientists should be more cautious about incorporating the Chandrasekhar Limit into their future work, they said.
Howell worked with California Institute of Technology professor Richard Ellis and Peter Nugent, a staff scientist at Lawrence Berkeley National Laboratory. Their research will be published Thursday in the scientific journal Nature.
Copyright 2006 Reuters. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. |
Experts rethinking how stars explode |
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