Document Type

Conference Proceeding

Publication Date


Published In

Active OB Stars: Structure, Evolution, Mass-Loss, And Critical Limits: Proceedings Of The 272nd Symposium Of The International Astronomical Union


X-rays give direct evidence of instabilities, time-variable structure, and shock heating in the winds of O stars. The observed broad X-ray emission lines provide information about the kinematics of shock-heated wind plasma, enabling us to test wind-shock models. And their shapes provide information about wind absorption, and thus about the wind mass-loss rates. Mass-loss rates determined from X-ray line profiles are not sensitive to density-squared clumping effects, and indicate mass-loss rate reductions of factors of 3 to 6 over traditional diagnostics that suffer from density-squared effects. Broad-band X-ray spectral energy distributions also provide mass-loss rate information via soft X-ray absorption signatures. In some cases, the degree of wind absorption is so high, that the hardening of the X-ray SED can be quite significant. We discuss these results as applied to the early O stars zeta Pup (O4 If), 9 Sgr (O4 V((f))), and HD 93129A (O2 If*).

Published By

Cambridge University Press


C. Neiner, G. Wade, G. Meynet, and G. Peters


IAU Symposium 272: Active OB Stars: Structure, Evolution, Mass-Loss, And Critical Limits

Conference Dates

July 19-23, 2010

Conference Location

Paris, France


This work is freely available courtesy of Kluwer.
This work is a preprint retrieved from at arXiv:1009.5669.