The formation of Be stars through close binary evolution.

The possibility that Be stars are the remnants of case B mass transfer in intermediate-mass close binaries is investigated. It is shown that only progenitors with mass ratios greater than a certain minimum value q-min are capable of producing a Be star after the mass transfer. The value of q-min lies between 0.3 and 0.5, depending on the evolution parameters as well as on the observationally determined lower mass limit of Be/X-ray binaries. In more than 80 percent of the predicted systems, the evolved companion is an He star, particularly among the late-type B stars; these systems may be detectable as XUV sources.