HIGH-ENERGY FLARE OBSERVATIONS FROM THE SOLAR MAXIMUM MISSION

We review high-energy observations of solar flares with emphasis on measurements by instruments on the Solar Maximum Mission satellite. Those observations show that, contrary to prior expectation, high-energy emission is a common property of solar flares. Direct interpretation of the measurements shows that both energetic ion and relativistic electron acceleration are ubiquitous flare phenomena and that those particles can be accelerated to high energies very rapidly. We present evidence that the high-energy emission from flares is anisotropic. We also review how studies of the nuclear line spectra have allowed derivation of characteristics of both the energetic ions and the target material. Altogether, these results clearly refute many of the old ideas about energetic flare particles and have stimulated new thinking about how particles are accelerated and transported during flares.