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