Time scales and energy of flares on red dwarf stars (a review).

Systematic studies on the energy and time scales of flares on UV Cet-type stars make it possible to draw some conclusions that must be accounted for in stellar flare theoretical models as well as in any general theory of flare activity. The most powerful flares of the type under consideration take place on stars of spectral classes K5-M0. The intrinsic frequency of flares is higher for absolutely brighter stars, although on fainter stars more frequent flares are determined. A detailed analysis of many dozen light curves of flares, recorded with time resolution of 3 x 10 to the -7th s, does not show significant structure with lifetime shorter than 0.1 s, which is what could be expected in the case when nonthermal mechanisms produce the flare optical radiation. The durations of fast flaring-up phases fit the predictions of gasdynamic models of stellar flares.