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Science/Tech See other Science/Tech Articles Title: Cosmic collisions likely caused gamma-ray explosion last Christmas Last Christmas, NASA’s Swift spacecraft detected a large gamma ray burst – the cause of which has been a puzzle to astrophysicists. Gamma ray bursts are large, high energy explosions that last only a short period of time. In just a few seconds, though, they emit more energy than the Sun will throughout its entire lifetime. While hundreds of gamma ray bursts have been studied and their mechanics well known, advances in detection have produced a few that don’t fit the mold – and the Christmas burst is one of those. “What the Christmas burst seems to be telling us is that the family of gamma-ray bursts is more diverse than we fully appreciate,” said Christina Thoene, astrophysicist in NASA’s release about the burst. “It’s only by rapidly detecting hundreds of them, as Swift is doing, that we can catch some of the more eccentric siblings.” Thereone’s team has studied the Christmas burst and believes that the most likely scenario for such a large explosion is a binary system of a star and a neutron star. A neutron star is the remnant of the explosion of a large star – stars much larger than the sun. After the star explodes, its mass is compressed to an extraordinary degree – making them perhaps the densest objects in the universe. In Thoene’s scenario, the neutron stars binary cousin entered into its red giant phase, expanding the star to the point that it collided with the neutron star. The end result of that merger would be the formation of a black hole, the creation of which would release large jets of gas, which would then have been followed by a weak supernova. If this scenario is correct, then the gamma ray burst happened billions of years ago – far away from the Earth. However, a different team has worked out an alternate scenario. This team, led by physicist Sergio Campana, suggests that the event happened much later, and the burst was only about 10,000 light years away from Earth. In this scenario, the gamma ray burst was caused by a large, comet-like object that fell into a neutron star. That debris would not only have produced the gamma ray burst, but also some X-ray emissions that were also observed from the explosion. It would be easy to determine which scenario is most likely to be the right one – if the distance of the burst could only be definitively determined. Unfortunately, neither Hubble nor ground based observatories were able to make a distance determination. Teams are still working on that problem, though. And apart from the distance issue, there may be other ways to find the right answer as well. The beauty of the Christmas burst, though, is that its very strangeness will let us learn even more about this wonderful universe. Post Comment Private Reply Ignore Thread
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