G.H. Share and R.J. Murphy Naval Research Laboratory, Washington, DC, USA
Solar gamma-ray lines and continua provide information on accelerated particles that interact at the Sun. We primarily discuss observations of flare spectra made by the OSSE experiment on CGRO and the gamma-ray spectrometer on SMM. Continuum gamma-ray spectra reflect the MeV electron population. These spectra show various shapes above 0.1 MeV: single power laws; broken power-laws, both hardening and softening > 0.1 to 0.2 MeV; and spectra that harden > 1 MeV. The spectra and directionality of accelerated protons and alpha particles are revealed in the lines from excited ambient nuclei and alpha-alpha fusion. These measurements yield power-law spectral indices between ~ -3 and -5 for energies >5 MeV, broad angular distributions, and high accelerated alpha/proton ratios (~0.5) in some flares. The presence of accelerated 3He is revealed in weak line features suggesting 3He/4He ratios of ~0.1 or greater. The composition and directionality of heavier accelerated ions are revealed by strongly Doppler- broadened lines. Fe appears to be enhanced by about the same ratio found in impulsive SEPs while the Ne-Mg-Si group may not be enhanced as strongly, suggesting that temperatures may be higher where the solar-interacting particles are accelerated.