No CrossRef data available.
Published online by Cambridge University Press: 14 August 2015
The envelopes of early type stars can be studied by comparing observed and theoretical P Cygni profiles of UV resonance lines. The lines are formed by scattering in the expanding envelope and complete frequency redistribution is a reasonable assumption. The Sobolev approximation can be used for the prediction of the profiles, except within a Doppler shift of 2xvthermal from the line center. The profiles are sensitive to the optical depth τrad(v) ∝L ni(r) (dr/dv), but insensitive to the velocity law. We present a fairly simple method to calculate the effects of a photospheric profile or partly overlapping doublets.