A correlation between time-overlapping solar flares and the release of energetic particles

Abstract

The origin of a large co-rotating solar particle event in August, 1970, is discussed. Proton data from spacecraft at five widely separated heliocentric longitudes are used to identify two distinct release points which are over 100° apart in solar longitude. Optical flare data shows a high incidence of time-overlapping flares between plage regions close to the two release points, indicating a good connection between them. Unusual X-ray and radio emissions are also observed from these regions. The spectrum of the relativistic electrons in the co-rotating particle event is represented by a power law with index γ ≈ −4, considerably steeper than that usually observed from a solar flare. It is concluded that there is a large magnetic loop structure connecting points over 100° apart on the Sun which is able to trap energetic protons and electrons from an earlier solar flare. Subsequent release of these particles establishes an intense, long-lived co-rotating event.