ELECTROMAGNETIC AND CORPUSCULAR EMISSION FROM THE SOLAR-FLARE OF 1991JUNE 15 - CONTINUOUS ACCELERATION OF RELATIVISTIC-PARTICLES

Data on X-, gamma-ray, optical and radio emission from the 1991 June 1 5 solar flare are considered. We have calculated the spectrum of proto ns that produces gamma-rays during the gradual phase of the flare. The primary proton spectrum can be described as a Bessel-function-type up to 0.8 GeV and a power law with the spectral index almost-equal-to 3 from 0.8 up to 10 GeV or above. We have also analyzed data on energeti c particles near the Earth. Their spectrum differed from that of prima ry protons producing gamma-ray line emission. In the gradual phase of the flare additional pulses of energy release occurred and the time pr ofiles of cm-radio emission and gamma-rays in the 0.8-10 MeV energy ba nd and above 50 MeV coincided. A continuous and simultaneous stochasti c acceleration of the protons and relativistic electrons at the gradua l phase of the flare is considered as a natural explanation of the dat a.