Conclusions
• There is a relatively wide variety of line profile morphologies seen in Chandra and XMM observations of OB stars, indicating that a surprising variety of high-energy physical processes are occurring in early-type stars
•Supergiants with massive radiation-driven winds have X-ray emitting plasma distributed throughout their winds: Standard wind-shock models explain the data if the mean optical depth of the cool wind component is several times lower than expected (mass-loss rates overestimated? clumping?)
•Young O and early B stars are well explained by the hybrid magnetically channeled wind shock model
•Normal B stars don’t fit neatly into any of these paradigms