Astron. Astrophys. Suppl. Ser. 132, 45-54

A series of theoretical line profiles formed in the irradiated expanding atmospheres of close binary components

A. Peraiah - M. Srinivasa Rao

Send offprint request: A. Peraiah
e-mail: anna@iiap.ernet.in

Indian Institute of Astrophysics, Koramangala, Bangalore-560034, India

Received March 20, 1997; accepted March 24, 1998

Abstract:

We studied the effects of irradiation on the line formation in the expanding atmospheres of the components of close binary systems. We considered a two-level atom approximation in Non-LTE situation. The thickness of the atmosphere is assumed to be twice that of the stellar radius. Expansion velocities are assumed to be as large as 50 mean thermal units. We have computed the lines using total optical depths 10³, 10⁴ and 10⁵ at the line centre. The irradiation from the secondary is assumed to be one, five and ten times the self radiation. The line fluxes in the line of sight are calculated by using the total source function which is the sum of the source functions due to self radiation and that due to irradiation. We notice that the expansion of the medium produces P Cygni type profiles and the irradiation enhances the emission in the lines although the equivalent widths reduce considerably.

Key words: radiative transfer -- lines: formation; profiles -- binaries: close