An expansion opacity formalism for the Sobolev method.
Abstract
We present a simple formalism for treating the opacity due to million of lines in atmospheres with large velocity gradients: i.e., an expansion opacity formalism. This formalism is for use with the Sobolev method of radiative transfer. The formalism assumes that lines act like twolevel atom lines with complete redistribution, the continuous absorption opacity is in local thermodynamic equilibrium, electron scattering is coherent, and source functions can always be approximated as isotropic. The essential feature of the formalism is that large numbers of lines are replaced by a much smaller set of artificial expansion lines. The formalism is relativistically correct. Demonstration calculations are presented.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 July 1995
 Bibcode:
 1995A&A...299..770J
 Keywords:

 RADIATIVE TRANSFER;
 RELATIVITY;
 SUPERNOVAE;
 STARS: ATMOSPHERES;
 METHODS: ANALYTICAL