Physical and gasdynamical processes caused by impacts of sun-grazing comets onto the sun

The physical and gasdynamical processes caused by cometary impacts onto the Sun and their manifestations are studied. Numerical radiation gasdynamics model taking into account ablation, spectral radiation, ionization, and radiative transfer of energy is developed. In the model we use the ion compositions close to those existing in the solar atmosphere and in the cometary substance vapor. Main stages of the fall are considered. We describe the characteristic features of these stages and estimate parameters of light flashes. We discuss the results from the viewpoint of the solar observations.