Astronomers Identify Supernova as Source of Cosmic Ray Protons

Astronomers from Argentina and South Africa have provided the first direct evidence for the origin of the most common cosmic rays, atomic particles that bombard the Earth at nearly the speed of light. Earlier observations showed that cosmic ray electrons are propelled toward the Earth by supernovas, but the origin of cosmic ray protons--which outnumber electrons 10 to one--has been in doubt.

The team will report today at a gamma-ray meeting in New Hampshire that they have identified a previously unrecognized supernova about 1,600 light-years from Earth and two nearby gamma-ray sources. The evidence indicates that the supernova accelerated protons toward nearby gas clouds, where they hit other protons and emitted gamma rays detected here. The team said this is the first proof that supernovas can eject protons at high speeds.

Compiled by Times medical writer Thomas H. Maugh II