Credit: Reeves et al., Nature 416, 512-515 (4 April 2002)
Post-mortem of a Monster's Death
Gamma ray bursts are the most powerful explosions ever seen in the
Universe. The cause of these explosions is controversial, and 2 models have
been put forth. One theory suggests that gamma ray bursts are produced by
the mergers of 2 neutron stars. The other suggests that gamma ray bursts
are produced by an extremely powerful supernova explosion of a stellar
monster (a star many times more massive than the sun) after the star uses
up its nuclear fuel. A recent
observation by the XMM-Newton
satellite of a gamma ray burst known as GRB011211 provides crucial
clues to resolve this controversy. These clues are contained in the X-ray
spectrum (shown above) of the burst's afterglow. For the first time
the XMM-Newton spectrum shows the presence of chemical elements like
magnesium, silicon and sulfur in the afterglow. These elements are thought
to have been produced during the final stages in the evolution of a massive
star just prior to the supernova explosion. In addition,
scientists measured the speed of this material and found it moving at 10%
of the speed of light. The "neutron-star" merger hypothesis could not
explain the amount of material seen in the XMM-Newton spectrum.
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Page Author: Dr. Michael F.
Corcoran
Last modified April 8, 2002
