Expanding atmospheres in non-LTE:

Radiation transfer using short characteristics

Professur Astrophysik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany

Corresponding author: L. Koesterke, lars@astro.physik.uni-potsdam.de

Received: 14 March 2001
Accepted: 10 October 2001

Abstract

We present our technique for solving the equations of radiation transfer in spherically expanding atmospheres. To ensure an efficient treatment of the Thomson scattering, the mean intensity J is derived by solving the moment equations in turn with the angle-dependent transfer equation. The latter provide the Eddington factors. Two different methods for the solution of the angle dependent equation are compared. Thereby the integration along short characteristics turned out to be superior in our context over the classical differencing scheme. The method is the basis of a non-LTE code suitable for the atmospheres of hot stars with high mass-loss.