Evidence for rotationally modulated variability in O star winds

Abstract

The nature of variability observed in the UV resonance line P Cygni profiles of four O stars is interpreted in terms of recurrent episodes of low-velocity broad absorption enhancements evolving into high-velocity narrow absorption components. Profile fitting techniques are used to determine the central velocities of the (multiple) features. The recurrence time-scale for the development of the absorption enhancements and their period of evolution appears to correlate with the projected rotational velocity of the stars. These results are briefly discussed in the context of some recent morphological and physical models.