Cosmic rays are atomic nuclei of mysterious origin that constantly bombard Earth. The discovery, made with the National Aeronautics and Space Administration's Chandra X-ray Observatory, supports theoretical arguments that shock waves from stellar explosions may be a primary source of cosmic rays.
Some astronomers believe cosmic rays are produced by solar flares. Others think they're caused by similar events on other stars, or pulsars or black hole accretion disks.
But one of the prime suspects has been supernova shock waves. Now, a team of astronomers has used Chandra observations of the nebula is known as Tycho's Supernova Remnant to strengthen the case for that explanation.
"With only a single object involved we can't state with confidence that supernova shock waves are the primary source of cosmic rays," said John Hughes of Rutgers University, co-author of a report to be published in an upcoming issue of The Astrophysical Journal. "What we have done is present solid evidence that the shock wave in at least one supernova remnant has accelerated nuclei to cosmic ray energies."