Using polarization to study the winds of massive stars

Ben Davies (1,2), Jorick S. Vink (3), Rene D. Oudmaijer (1)

(1) University of Leeds, UK; (2) R.I.T., USA; (3) University of Keele, UK.

The topic of wind-clumping has been the subject of much activity in
recent years, due to the impact that it can have on derived mass-loss
rates. Here we present an alternative method of investigating
wind-clumping, that of polarimetry. We present simulations of the
polarization produced by a clumpy wind, and argue that the
observations may be reproduced just by statistical deviations from
spherical symmetry when the outflow is only slightly fragmented. Here,
the polarization scales with $\dot{M}$, which is consistent with
observations of LBVs, WRs and O supergiants. Finally, we find clumping
factors in the inner 2$R_{\star}$ of $\sim 2-3$, and speculate as to
the clumping stratification of hot stars.

Reference: to appear in proceedings of 'Mass loss from stars and the evolution of stellar clusters'
Status: Conference proceedings