'Christmas Day' cosmic flash may have been dying comet

A burst of gamma-ray radiation from a distant galaxy, detected by an orbiting US telescope last December 25, may have come from a comet crashing into a neutron star, astrophysicists suggest on Wednesday. Gamma-ray bursts, or GRBs, are high-energy releases that often come from stars in their death throes. The so-called Christmas Day GRB, spotted by NASA's Swift radiotelescope, has excited huge debate. Its gamma emissions lasted for at least half an hour, whereas the typical GRB lasts from just a couple of second to a few minutes, and its emissions in the X-ray part of the energy spectrum faded much faster than usual. Poring over the data, a team led by Sergio Campana of the Brera Astronomical Observatory in Italy believe that the strange event was caused by a minor body such as a comet or asteroid that flew so close to a neutron star that it was ripped apart by gravitational force. Its crashing fragments produced a prolonged series of mini gamma-bursts. Another explanation, offered by Christina Thoene of the Institute of Astrophysics in Andalucia, southern Spain, is that the big GRB was the merger of a helium star and a neutron star, which created a supernova. The two papers are published in the British science journal Nature.