Spectropolarimetric variability in OB stars

Abstract

Data from the Wisconsin spectropolarimetric monitoring program provide information about the polarimetric variability of numerous types of stars. Examining the data that exist thus far, we find, not surprisingly, that many OB stars, especially OB supergiants and Be stars, are polarimetric variables. Be stars show the most extreme variable as a class. Results from the Be star pi Aqr are presented which illustrate the dramatic polarimetric variability that such stars can exhibit. Contemporaneous IUE data show that the development of low velocity discrete absorption components in the UV wind lines may be associated with the onset of polarimetric outbursts. These preliminary findings add further support to the picture that winds from hot stars are non-homogeneous and variable.