The flux deficits in star spots

The bolometric flux deficits of the photospheres of spotted stars are deriv ed for the first time in the framework of zonal spottedness models for red dwarfs computed at the Crimean Astrophysical Observatory. The resulting Bur deficits are compared to the estimated radiative losses from the chromosph eres and coronas measured during quasi-simultaneous observations. A linear correlation is found between the logarithms of these quantities, with the S un fitting these relations. Radiative losses from the outer stellar atmosph eres in quiescence and during individual sporadic hares are significantly l ower than the bolometric deficits of the spotted photospheres of active sta rs. This suggests that the flux deficit due to spots leads to global recons truction of the atmospheres of red dwarfs, analogous to the local atmospher ic reconstruction that occurs during solar and stellar hares. This process may be realized via the superposition of a large number of weak impulsive h ares and other dynamic events, which develop on these stars and heat their coronas (i.e., in this view, microflaring is favored as the principal coron al heating mechanism for these stars). A brief analysis of the long-term va riations in the chromospheric and photospheric radiation of FK stars from t he HK project and of the Sun suggests that such dynamical reconstruction of the outer atmosphere by energy associated with the flux deficit of the spo tted photosphere occurs at times of increased surface activity in all FM st ars. (C) 2001 MAIK "Nauka/Interperiodica".