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Cosmic Rays Linked to Supernova
By Kenneth Silber
Staff Writer
posted: 10:45 am ET
17 September 1999
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cosmic_rays_originAn international team of astronomers has gathered data on a subject long dominated by theory and speculation: the origin of cosmic rays. Cosmic rays are particles -- mostly protons -- that bombard Earth at nearly the speed of light. Seeking a mechanism to explain such high speeds, theorists have long pointed to supernovas, the explosions of massive stars. Such explosions could speed up particles that are floating in interstellar space. "We collected the first direct observational evidence that protons are accelerated by supernova explosions," says team member Gustavo E. Romero, a research scientist at the Argentine Institute for Radio Astronomy (Instituto Argentino de Radioastronomia). Using a radio telescope in South Africa, the team detected a previously unknown cloud of gas, the remnant of a supernova that occurred 16,000 years ago. They then correlated this observation with readings from the orbiting Compton Gamma Ray Observatory, a NASA scientific spacecraft. The spacecraft had detected gamma rays that result from collisions among high-speed protons. Past observations indicated that supernovas speed up electrons, which constitute a less common type of cosmic ray. However, evidence of proton acceleration had been "elusive" until now, says Romero. In addition to Romero, the team included Jorge A. Combi and P. Benaglia of the Argentine Institute of Radio Astronomy, and Justin L. Jonas of Rhodes University in South Africa. The team reported its findings at the 5th Compton Symposium, a conference held in New Hampshire in mid-September.
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