Facultad de Ciencias Astronómicas y Geofísicas, Paseo del Bosque S/N, 1900 La Plata, Buenos Aires, Argentina

We compute non-LTE Mg II line profiles for Be stars by considering 12 energy-level atoms, and supposing that the circumstellar medium can be described by an expanding spherical symmetric flow in which we assume the presence of a chromosphere. The line radiative transfer equation was solved rigorously in spherical coordinates and in the comoving-frame. The Mg II line profiles predicted by this model coincide with those observed in some Be stars. The calculation was performed for a range of effective temperatures representative of the B spectral type. We have also analyzed the influence on the line profiles of different temperature and velocity distributions in the circumstellar material. The line spectrum variability of a Be star is interpreted as the result of a variable outward mass flux.

1998, ApJ, 502, 824