Effects of Dust in Distorted, Irradiated, and Expanding Atmospheres of Close Binary Components

Abstract

We studied the transfer of line radiation with dust in distorted and expanding atmospheres of close binary components. We assumed that the distortion of the atmosphere is caused by self rotation and a tidal force exerted by the presence of a secondary component. A seventh degree equation is defined to describe the distorted surface for uniform rotation. The equation of line transfer in the presence of gas and dust is solved in the comoving frame of the expanding atmosphere of the primary component in a binary system. We have considered a complete redistribution of photons in the line and that dust scatters radiation isotropically. We used a linear law of velocity of expansion so that the density varies as r-3, where r is the radius of the star, satisfying the law of conservation of mass. We noticed that considerable changes occur in line fluxes in dusty and dust-free atmospheres. The expansion of the atmosphere produces double-peak emission lines with P Cygni characteristics. These emission peaks are reduced in a dusty atmosphere.