ShareThisAbout 7 1/2 billion years ago, long before our solar system was born, a massive star exploded and collapsed in on itself.The light from that explosion arrived here this year, at precisely 2:13 a.m. on March 19. The blast created the strongest gamma ray burst ever recorded in the universe, and the resulting light glowed so brightly that it could be seen for 40 seconds by the naked eye.The burst, officially known as GRB 080319B, was first detected by the National Aeronautics and Space Administration's Swift satellite, which is managed by Penn State University. The satellite relayed the information quickly to ground-based telescopes around the world, and the resulting frenzy of analysis has culminated in studies being published this week by more than 90 astronomers in the journal Nature.David Burrows, a Penn State astronomer who heads the Swift science operations team, said it is almost impossible to come up with a good analogy for how powerful this burst of radiation was and how luminous its afterglow has been.But he noted that if a similar supernova had occurred in this galaxy, it very likely would have altered Earth's atmosphere so much that the skies would have darkened and we would have entered a "nuclear winter."GRB 080319B started with a massive star exploding in the constellation Bootes, which overlooks Ursa Major. When these massive stars fall in on themselves and create either a neutron star or black hole, they eject jets of gas that light up the material around the star, a team of astronomers explained in a news conference.This gamma ray burst was unusual for two reasons.First, it was aimed directly at Earth, which happens only once every decade. "Most of the time the narrow jet (from a collapsing star) is not pointed directly at us," said Penn State graduate student Judith Racusin, lead author of the Nature paper, "but in this case, due to unusual circumstances, it was."Second, analysis of the radiation streaming from the star showed it probably had two overlapping gas jets, an extremely narrow, ultrafast one in the center, and another about 20 times wider surrounding it.The Swift telescope picks up about 100 gamma ray bursts a year, only a small fraction of all that occur.GRB 080319B -- its name includes the year, month and date -- is by far the brightest ever registered, easily eclipsing the previous champion, GRB 990123, and it already has its own Wikipedia page, the astronomers noted.One other exciting component of its discovery was how it has added to astronomers' understanding of how the universe evolved.The intense illumination of the gamma ray burst allowed astronomers to take spectroscopic measurements of the light as it moved through space, and that helped prove that the universe has become chemically richer as time has unfolded, because exploding stars seed space with new elements that have been cooking in their interiors.To see an artist's rendering and animations of the gamma ray burst, go to www.science.psu.edu/alert/Swift9-2008.htm. E-mail Mark Roth at mroth(at)post-gazette.com (Distributed by Scripps Howard News Service, www.scrippsnews.com.)
Light from exploding star arrives 7.5 billion years later
Submitted by SHNS on Fri, 09/12/2008 - 13:12
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