Abundance Determinations from Gamma Ray Spectroscopy

Gamma ray emission lines resulting from accelerated particle bombardment of ambient gas can serve as an important spectroscopic tool for abundance determinations. The method is illustrated by considering the gamma ray line emission observed from solar flares. The observation of similar gamma ray lines from Orion suggests the existence of large fluxes of low energy Galactic cosmic rays. The role of these cosmic rays in the nucleosynthesis of the light isotopes is discussed.