A subdwarf's startling stellar wind.

Abstract

Selected observations of the subdwarf HD 128220B are presented to illustrate several remarkable properties of its stellar wind. The N V resonance doublet shows a typical P Cygni profile, but the C IV doublet shows a highly structured, strongly variable absorption profile with up to nine discrete velocity components present at any one time. Velocities and column densities are estimated from these data using profile fitting techniques. Some implications of the results are briefly discussed; in particular, the presence of redshifted absorption features is shown to offer a constraint on the subdwarf's mass.