The 'SEI' method for accurate and efficient calculations of line profiles in spherically symmetric stellar winds

Abstract

A new method for calculating line profiles formed in spherically symmetric stellar winds in which the velocity increases monotonically outward is described. The source function is calculated with the escape probability method, but the transfer equation is solved exactly. The method allows the calculation of singlets and doublets with underlying photospheric absorption components. Profile comparisons show that the presented method often attains the same accuracy as profiles calculated with the comoving frame method but has the advantages of the escape probability method. It can be run on a small computer and requires little CPU time, so that it can be used in an interactive analysis of observed line profiles.