Discrete absorption components : a study of the gas parcel model using component velocity observations.

Abstract

Available IUE spectra for Beta Ori are used to test the model (Underhill and Fahey, 1984) of the release of discrete parcels of gas from above the stellar photosphere as a possible origin for the discrete absorption components noted in UV spectra. The applicability of late-B supergiants to the present parcel model is questioned. It is suggested that stellar wind acceleration laws must be improved for such stars, taking into account the increasing importance of neutral hydrogen in the calculation of radiation pressure.