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Gamma-Ray Bursts May Be Born in Stellar Nurseries

Gamma-ray bursts¿the mightiest explosions in the universe¿may share their birthplace with baby stars, researchers report. As such they could help point the way to these stellar nurseries, which are often cloaked in cosmic dust. The new findings were announced yesterday, at the Gamma Ray 2001 conference in Baltimore, Md.

Luigi Piro of the Consiglio Nazionale delle Ricerche and his colleagues based their conclusion on data collected by NASA's Chandra X-ray Observatory and the Italian and Dutch satellite BeppoSAX. "We know that when a gamma-ray burst explodes, it produces a blast of material called a fireball, which expands at relativistic speeds like a rapidly inflating bubble," Piro explains. "Our team found evidence that the blast wave caused by the fireball brakes against a wall of very dense gas, which we believe is the crowded region where stars form."

The new observations support the theory that gamma-ray bursts result from the explosion of massive stars known as hypernovae. Because the brawny star required for a hypernova explosion matures so quickly, the blast may occur in the same region that gave birth to the star in the first place. Furthermore, that explosion might itself spur additional star formation.

Unlike the optical light waves that emanate from stars, gamma rays easily penetrate the dust and gas clouds that often obscure stellar births. "If one in every 100 of those [infant stars] explodes in a gamma-ray burst," Fiona Harrison of the California Institute of Technology told Reuters, "then that will shine through and you can say, aha, that's where stars are made."

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