Refractory Nuclides in the Cosmic-Ray Source

Abstract

New observations of the abundances and energy spectra of the isotopes of Mg, Al, and Si from ACE/CRIS are used to extend our previous results on the composition of refractory nuclides in cosmic-ray source material. For the 18 nuclides considered for elements between Mg and Ni, relative source abundances are generally consistent with solar-system values to within 20%. The ^(58)Fe abundance, taken relative to ^(28)Si, is found to have the largest difference from solar, a factor of ∼ 1.6. We suggest that the compositional similarity between the cosmic-ray source and the solar system can be understood in terms of acceleration of cosmicray refractories out of a well-mixed sample of interstellar matter.

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