Model of expanding atmosphere for HD 50138

Abstract

The Be star HD 50138 displays an important infrared excess. The aim of the present investigation is to study the effect of the physical processes - i.e., bound-free transitions, free-free transitions, and electron scattering - on the radiation field originated in the central star. We have proposed, on observational basis, the existence of a chromosphere and a stellar wind. Under these constraints, we have solved the transfer equation by an observer's frame calculation of it in spherical geometry and by applying the Feautrier method, in order to compute the emergent flux. We have computed the continuum radiation for different velocity-laws, which turned out to be in very good agreeent with the IRAS observations in 12, 25, 60, and 100 μ.