Apr 4 2002
From The Space Library
In an article in the journal Nature, astronomers at ESA reported that they had found evidence indicating which specific type of stellar object produces gamma-ray bursts (GRBs), the universe's most energetic phenomena. Prevailing hypotheses had posited that, either GRBs originate from the merger of two neutron stars, or they form from the collapse of one massive star, but researchers had discovered no conclusive proof to support either of these ideas. However, based on their analysis of the speed, temperature, and chemical elements of a GRB that had occurred on 11 December 2001, ESA astronomers found evidence supporting the latter hypothesis. The research team examined two sequential observations of the GRB, both taken by ESA satellites: the BeppoSAX satellite had made the first observation, and, nearly 11 hours later, the XMM-Newton satellite had made the second. The team had found large quantities of argon, calcium, magnesium, silicon, and sulphur, moving at 1/10th the speed of light. These findings supported the idea that a supernova explosion from a single massive star produces GRBs. If the merger of two neutron stars had produced the burst, astronomers would have expected the stars to produce large amounts of elements other than those observed~particularly iron~and to emit those elements at a slower velocity. (J. N. Reeves et al., “The Signature of Supernova Ejecta in the X-ray Afterglow of the ?-ray Burst 011211,” Nature 416, no. 6880 (4 April 2002): 512-515; ESA, “ESA's X-ray Space Telescope Proves Supernovae Can Cause Mysterious Gamma-Ray Bursts,” ESA news release 22-2002, 4 April 2002.)
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