Two Classes of Gamma-Ray/Proton Flares: Impulsive and Gradual. Revision,

Abstract : We have studied various properties of gamma ray/proton flares, which produce nuclear gamma rays and/or interplanetary energetic protons. We have found that there exist two classes of gamma ray/proton (GR/P) flares, with each class having many distinct characteristics in common. Gradual GR/P flares (so named because of gradual variations of hard X-ray fluxes with duration of spike bursts longer than 90 s) have the following characteristics: long duration ( 10 min) hard / X-ray and microwave emission, gradual variation of microwave flux, relatively large ratios of microwave to hard X-ray fluxes, large H-alpha areas, long-duration soft X-ray emission ( 1 hr), hard X-ray emission from extended coronal loops, interplanetary type II emission, coronal mass ejections, and production of large numbers of interplanetary energetic protons. Impulsive GR/P flares display directly opposing behavior in the above respects. However, the two classes of GR/P flares have a few characteristics common to both of them.