On thermalization of radiation in hydrostatic atmospheres

Abstract

The problem of thermalization of radiation within a self-emitting hydrogen isothermal atmosphere is considered for the case of a hydrostatic profile of the plasma density. The probabilistic approach to define the thermalization depth for the photon of a given frequency is used. Quantitative conclusions are made on the value of the optical depth at which the radiation can be viewed as thermalized up to a given frequency. The analytical and numerical solutions of the radiative transfer equation confirm the obtained results. The frequency dependencies of the probability of free-free absorption of a photon due to single interaction in a cold nonmagnetized and magnetized plasma are calculated.