A cosmic-ray composition controlled by volatility and A/Q ratio. SNR shockacceleration of gas and dust

The composition of Galactic Cosmic Ray Sources (GCRS) shows. the following features: (i) an enhancement of the refractory elements relative to the Vol atile ones, and (ii) an enhancement of the heavier volatile elements relati ve to the lighter ones; this mass dependence should reflect a mass-to-charg e (A/Q) dependence of the acceleration efficiency; among the refractory ele ments, there is only a very weak enhancement of heavier species, or none at all. We consider it fortuitous that the GCRS composition resembles that of the solar corona, which is biased according to first ionization potential. In a companion paper by Ellison et al. (1998, this issue), this GCRS compo sition is interpreted in terms of a supernova shock wave acceleration of in terstellar and/or circumstellar (e.g., Ne-22-rich Wolf-Rayet wind) gas phas e and especially dust grain material. These two papers summarize and comple ment the content of two papers that recently appeared in Astrophys. J. (Mey er et al., 1997; Ellison et al., 1997).