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
¥ Maybe some unusual objects like the Be star g Cas have magnetic dynamos, perhaps due to star-disk interactions
¥ Normal B stars donÕt fit neatly into any of these paradigms