|ESA Science & Technology||30-Jun-2005 16:44:23|
Beyond the Heliosphere
Cosmic gamma-ray bursts are the most powerful explosions in the known universe. They appear to be generated by the collapse of very massive stars (~100 solar masses). One of Ulysses' scientific objectives is to be flagship of the 3rd Interplanetary Network (IPN) of gamma-ray burst detectors, which locates bursts precisely by comparing their arrival times at widely separated spacecraft. The distances to about a dozen sources have now been measured, showing that they are at cosmological distances comparable to those of quasars. If the bursts emit their energy uniformly into space, their output is 1053 erg in gamma-rays alone. In addition to being interesting in their own right, gamma-ray bursts are being used by cosmologists as probes of the early universe.
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