Origin of Cosmic Rays, Atomic Nuclei, and Pulsars in Explosions of Massive Stars

Abstract

Explosions of massive stars (8 M/M0 70) are examined as the source of Galactic cosmic rays. Detailed nucleosynthetic and evolutionary calculations suggest that these massive stars produce the heavy elements (Z > 6) in their proper relative abundances. This is particularly significant because lower-mass stars (in particular the 4-8 M0. range) are unable to produce the observed abundances of C and 0 relative to the iron peak. A small ( 1.4 M ) dense remnant star left after the explosion may provide a location for an electromagnetic acceleration mechanism. Those abundance ratios which can now he predicted (He, C, 0, Ne, Mg) for the material to be accelerated by the pulsar give a reasonable match to the observed cosinic-ray data. The conditions at the outer edge of the remnant and the inner edge of the ejected material may he appropriate for an r-process to occur; the high-Z cosmic rays seem to show an enrichment of r-process material. It appears that these stars may be the astrophysical source for the Galactic cosmic rays. Subject headings:cosmic rays - pulsars - stellar evolution - supernovae