A Comparison of Models of Cosmic-Ray Source Composition

Several models for the origin of cosmic rays have been proposed to explain the relative differences of cosmic-ray source abundances and the general abundances of elements and isotopes. One model, for example, assumes injection at normal stars like the sun, using FIP-modified coronal rather than photospheric abundances. Another with acceleration and breakup of grains by supernova shock waves has been popular with several authors. On the basis of the known abundances of few elements, we demonstrate how a critical evaluation of one model's merits against the others can be made.