On Activities of UV Cet-Type Flare Stars and of T Tau-Type Stars

Abstract

Comparisons of the activities of UV Cet-type flare stars and of T Tau-type stars with solar activity permits the conclusion that non-stationary processes in the UV Cet-type stars and in the Sun are of an indentical physical nature hut that they differ qualitatively from active events in the T Tau-type stars. The identity of the activity in flare stars and the Sun makes it possible to study successfully stellar activity with the help of known models of various solar events and, on the other hand, to have a more general approach to the physics and evolution of solar activity on the basis of established features of numerous flare stars of different ages and masses. The hypothesis on hydromagnetic activity of the T Tau-type stars is sketched; within this framework, one supposes that the main feature of such stars is an occurrence at every point of the stellar surface, of conditions necessary for the existence of dark spots, i.e. a lowering of the photospheric brightness due to strong local magnetic fields. It is noted that the total energy losses from non photospheric radiation of flare stars are comparable in power to the total radiation deficit of dark spots on such stars.