Time evolution of an ensemble of relativistic electrons in a non-homogeneous atmosphere

Abstract

The flaring and quiescent radio emission of RS CVn stars has been interpreted in terms of the time evolution of a population of electrons injected in the source at the beginning of the flare and then undergoing energy losses [1]. A uniform source with a locally constant magnetic field was assumed. In this paper new calculations of the time evolution of the electron population are presented. A more realistic magnetic field configuration reproducing a bipolar starspot group is considered and the thermal absorption is taken into account. The time evolution of the spectrum and of the brightness distribution, in the extreme configuration of a loop viewed face-on, are shown and compared with available spectral and VLBI observations.