OEBE-STARS WITH POSSIBLE COMPACT COMPANIONS OBSERVED AT X-RAYS

A survey of bright O- and B-type stars has been conducted from the ROSAT All Sky Survey data, aiming at the detection of compact companions expected for Oe and Be stars. Concurrent H alpha spectroscopy has been used to establish the level of activity of these stars around the time of the X-ray observations. The detection rate of OB and OeBe stars as well as their average X-my over bolometric luminosities suggest little difference between these two groups of objects, Instead of accretion onto a compact object (NS, WD), the X-ray emission from OeBe stars may be produced by stellar winds as has been proposed for O- and early B-type stars in general. Flexibilities in the available models for X-ray emission from accreting WDs may allow the X-ray emission from such objects to remain below a detectable level. These investigations are now being extended to pointed observations in the ROSAT Archive.