The effects of clumping on wind line variability

TL;DR

This paper explores how clumping in stellar winds affects resonance doublet profiles, revealing that analyzing these profiles can provide detailed insights into wind structure and variability.

Contribution

It demonstrates that doublet profiles contain more information than previously utilized by allowing the oscillator strength ratio to vary, revealing wind clumping effects.

Findings

Doublet profiles can vary between unity and the ratio of oscillator strengths.

Clumping affects the doublet profile ratios as a function of velocity and time.

Modeling shows how doublet analysis can reveal wind structure details.

Abstract

We review the effects of clumping on the profiles of resonance doublets. By allowing the ratio of the doublet oscillator strenghts to be a free parameter, we demonstrate that doublet profiles contain more information than is normally utilized. In clumped (or porous) winds, this ratio can lies between unity and the ratio of the f-values, and can change as a function of velocity and time, depending on the fraction of the stellar disk that is covered by material moving at a particular velocity at a given moment. Using these insights, we present the results of SEI modeling of a sample of B supergiants, zeta Pup and a time series for a star whose terminal velocity is low enough to make the components of its Si IV 1400 doublet independent. These results are interpreted within the framework of the Oskinova et al. (2007) model, and demonstrate how the doublet profiles can be used to extract infromation about wind structure.