Scientists catching cosmic rays with a NASA spacecraft have tightened the constraints on the evolving theory of how atoms travelling at nearly the speed of light are produced in stars and are strewn across the Universe through star explosions, or supernovae. A computer-generated impression of the ACE spacecraft.
Cosmic rays bombard the Earth's atmosphere constantly.
Rather, it is material that has been sitting around for hundreds of thousands of years that gets accelerated by the shock wave of a supernova explosion. Hink said the team found in their cosmic ray collection that this decay process had already run its course. This means that Ni-59, formed in one supernova explosion, sat decaying for over a 100,000 years before another supernova blast wave came along and propelled it into the surrounding galaxy at cosmic ray energies. Hink said that once an atom of Ni-59 is accelerated to cosmic ray energies and loses its electrons, it is relatively stable and invulnerable to decay, as long as it keeps moving. Dr. Mark Wiedenbeck of NASA's Jet Propulsion Laboratory, a member of the CRIS team, said their results rule out the possibility of the cosmic ray seed particles being fresh supernova ejecta.