An X-ray flare on the short-period, eclipsing binary UMa.

Abstract

An EXOSAT observation of a flare on the short-period, eclipsing RS CVn binary system XY UMa is reported. The light curve is interpreted within the framework of cooling plasma within loop-like magnetic structures, and limits on the flaring plasma and magnetic field parameters are derived using the light curve decay time and flare emission measure. The flare is similar to those observed on other RS CVn systems but not to those occurring on dMe stars. The comparative lack of optical flares on RS CVn stars is discussed in terms of a neutral beam model for the initial heating process in stellar flares.