Comoving Frame Calculations of Spectral Lines formed in Rapidly Expanding Media with the Partial Frequency Redistribution Function for Zero Natural Line Width

Abstract

Comoving frame calculations have been used to compute the spectral lines formed in rapidly expanding spherical media. We have employed the angle-averaged partial frequency redistribution function R(I) with a two-level atom model in non-LTE atom approximation. A linear velocity law increasing with radius has been employed with maximum velocity at tau=o being set equal to 30 mean thermal units. It is found that one obtains almost symmetric emission line profiles at large velocities similar to those found in quasars.