THE HYDROGEN-ATOM KINETICS IN SOLAR AND L ATE-TYPE STARS ATMOSPHERES

The Sobolev method for a medium with considerable velocity gradients g eneralized for a motionless medium with large optical thickness. The v alues of photon escape probability (Net Radiative Bracket) are calcula ted with an account for photon multiple scattering with simultaneous a ction of Stark and Doppler effects for absorption coefficients. The co mmon results of solution of stationarity equations with use of probabi lity consideration of radiative transfer equations are close to the re sults of earlier calculations for media with velocity gradients. The i nfluence of exterior photospheric radiation is taken into account, the effect of this influence is maximum in the case of low electron densi ties. The two important cases with medium parameters close to chromosp heric and low-temperature flare condensation conditions are presented as illustrations. This method is proposed for quantitative interpretat ion of flare Balmer decreements in solar and late-type stars' atmosphe res.