Line formation in expanding extended atmospheres with spherical geometry

Abstract

We have adapted the ETLA code prepared by D. Mihalas and P. Kunasz, (Ap. J. 219, 635, 1978). This code solves, in the comoving-frame, the radiative transfer equation with spherical geometry, in non-LTE, for a seven-level hydrogen atom, given a monotonic increasing velocity law and the temperature law given by C. Catala, P. Kunasz, and F. Praderie (Astron. Astrophys. 134, 402, 1984). From the calculation of theoretical line profile of Hα and Hβ, we observed the influence of a velocity gradient to the features of the profile, taking from P Cygni type profiles to lines with both wings in emission and with a central absorption profile. The influence of the temperature law on the emission profile is negligible for parameters as maximum temperature and cromosphere's extension but depend strongly upon position and temperature of the minimum region temperature place before reaching the maximum.