Constraints on the nucleosynthesis of refractory nuclides in galactic cosmic rays

Abundances of the isotopes of the refractory elements Ca, Fe, Co, and Ni in the galactic cosmic-ray source are compared with corresponding abundances in solar-system matter. For the 12 nuclides considered, relative abundances agree to within a factor of 2, and typically within 20–30%. In addition, comparisons of cosmic-ray abundances with model calculations of supernova yields are used to argue that cosmic rays contain contributions from stars with a broad range of masses. Based on these and other results we suggest that cosmic rays probably represent a sample of contemporary interstellar matter, at least for refractory species.