Spectral line formation in YY ORI envelopes : a multilevel hydrogen atom.
Abstract
A numerical method for incorporating a manylevel atom into the generalized Sobolev theory is presented. The basic, statistical equilibrium equations and Sobolevtype equations for the line radiation fields are reviewed, and the method of solution is set forth, including the treatment of rate equations, calculation of the coupling integrals, integration of flux profiles, and application to Balmer lines of spherical protostars. The results are compared with observations of YY Orionis stars, and it is found that the manylevel ansatz is successful in several ways, particularly in the reduction in model envelope density. The detailed shape of the line profiles is not reproduced, however, and the model profiles are too uniform and in particular cannot explain the observed differences between the hydrogen alpha line and higher Balmer profiles.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 May 1982
 Bibcode:
 1982A&A...109..245B
 Keywords:

 Hydrogen Atoms;
 Line Spectra;
 Orion Nebula;
 Protostars;
 Radiative Transfer;
 Stellar Envelopes;
 Stellar Evolution;
 Balmer Series;
 Late Stars;
 Radiation Distribution;
 Stellar Models;
 Astrophysics