Radiation transfer using short characteristics

We present our technique for solving the equations of radiation transfer in spherically expanding atmospheres. To ensure an ecient treatment of the Thomson scattering, the mean intensityJ is derived by solving the moment equations in turn with the angle-dependent transfer equation. The latter provide the Eddington factors. Two dierent 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 dierencing scheme. The method is the basis of a non-LTE code suitable for the atmospheres of hot stars with high mass-loss.