| Subject: gamma-ray burst |
Author:
Mike buzz
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Date Posted: 17:14:23 03/22/03 Sat
Scientists have witnessed the death of a gigantic star and the birth of a , quite possibly , brand new, spinning black hole.
The observation of a gamma-ray burst just moments after the explosion, is the most detailed to date. The observation confirms that gamma-ray bursts announce the demise of the most massive stars in the universe, a theory called the collapsar model. NASA's High-Energy Transient Explorer (HETE), ground-based robotic telescopes, and fast-thinking researchers around the globe, made the prompt observation possible.
Gamma-ray bursts shine hundreds of times brighter than a supernova, or as bright as a million trillion suns. The mysterious bursts are common, yet random and fleeting. The gamma-ray portion of a burst typically lasts from a few milliseconds to 100 seconds. An afterglow, caused by shock waves from the explosion sweeping up matter and ramming this into the region around the burst, can linger for days or weeks in lower-energy forms of light, such as X rays or visible light.
A gamma-ray burst, named GRB021004, appeared on October 4, 2002, at 8:06 a.m. EDT. Wasting no time, HETE spotted the burst, nailed down a location, and notified observers worldwide within a few seconds, while the gamma rays were still pouring in. First on the scene was the Automated Response Telescope (ART) in Wako, Japan, observing the region just 193 seconds after the burst.
These findings support the collapsar model, where the core of a massive star collapses into a black hole. The black hole's spin or magnetic fields may be acting like a slingshot, flinging material into the surrounding debris. Scientists calculated that GRB021004 originated from a star 15 times more massive than the Earth’s sun.
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