ИСТИНА

When interpreting recent observations of the optical continuum during large impulsive flares on the Sun and red dwarf stars, it is necessary to consider two components, blue and red continua. The first component, blue one, is associated with the radiation of the downward moving low-temperature condensation that is forming as a result of the explosive evaporation of the chromosphere. The optical continuum and line emission are calculated in the frameworks of the gas-dynamic modeling of the response of the chromosphere to the impulsive heating by accelerated electrons. For this component, there is a good agreement of the advanced model by Kostyuk-Pikelner and observations. The second component, the red continuum, is apparently due to the impulsive heating of layers adjacent to the temperature minimum that leads to an increase of the temperature in ~1000 K. We discuss possible origin of such a heating that can be, in particular, associated with the direct heating by accelerated high-energy particles. Features of absorption of the radiation by the negative hydrogen ion are considered. For the largest flares, we discuss a cause of similarity of the temporal profiles of both component of the optical continuum.