Post by Chicago Astronomer - Astro Joe on Jun 2, 2005 9:58:36 GMT -6
Leading Theories of Cosmic Explosions Contradicted
Observations of a cosmic explosion detected on Feb. 15 by two NASA satellites have thrown into doubt one popular explanation for such explosions and have also seriously weakened the argument for yet another, according to University of Chicago astrophysicist Don Lamb. But solving the mystery any time soon may be forestalled by plans to shut down one of the satellites in September.
The explosion in question is a powerful burst of X-rays called an X-ray flash that was observed by NASA's Swift and High Energy Transient Explorer-2 satellites. X-ray flashes seem to be related to gamma-ray bursts, the most powerful explosions in the universe. "No one understands this relationship at all. It's a complete mystery," said Lamb, the Louis Block Professor in Astronomy & Astrophysics at the University of Chicago and a member of the HETE-2 science team.
Lamb presents some ideas on the relationship of X-ray flashes to gamma-ray bursts during a meeting of the American Astronomical Society in Minneapolis. The co-authors of his paper are Tim Donaghy, a Ph.D. student in physics, and Carlo Graziani, Senior Research Associate in Astronomy & Astrophysics, both at the University of Chicago.
Discovered in 1969, Gamma-ray bursts last anywhere from fractions of a second to many minutes and pack the output of as many as 1,000 exploding stars. They occur almost daily, come from any direction in the sky, and are followed by afterglows that are visible for a few days at X-ray and optical wavelengths.
More here at RedNova: www.rednova.com/news/display/?id=153238&source=r_space
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The jury is still out, and I think it's too early to tell.
And yet another mission scrubbed!