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*).
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
July 19-23, 2010
David H. Cohen; Emma Edwina Wollman , '09; and M. A. Leutenegger.
"X-Ray Spectral Diagnostics Of Activity In Massive Stars".
Active OB Stars: Structure, Evolution, Mass-Loss, And Critical Limits: Proceedings Of The 272nd Symposium Of The International Astronomical Union.