ИСТИНА

Optical observations of largest flares on the Sun and other late-type stars are discussed. It is shown that such extremal events occur on young stars with rotational periods from < 1 day to 7-12 days. A joint analysis of data on superflares and available observations of stellar magnetic fields allows us to estimate the maximal flare energy. If we suppose that the origin of stellar superflares is similar to what leads to the most powerful non-stationary phenomena on the Sun, so the main process here is the acceleration of a huge number of particles up to high energies, which occurs near spots, in areas of strong magnetic fields. The area of the source of the flare optical continuum emission appearing as a result of the gas-dynamical response of the chromosphere to the heating by the powerful hard flux of accelerated electrons is 2–3 orders of magnitude larger than the area of white-light solar flares. Observational consequences of such a model are discussed.