The progenitors of Be-stars paired with O-subdwarfs: the spin-up of a Be star at the stage of conservative mass exchange

The spinning-up of the accreting component in the process of conservative mass exchange is considered in binary systems - progenitors of systems consisting of a main sequence Be-star and an O-subdwarf. During the mass exchange, the meridional circulation transfers 80-85% of the angular momentum that entered the accretor together with the accreted matter to the accretor surface. This angular momentum is removed from the accretor by the disk. When the mass exchange finishes, the accretor has a rotation typical of classical Be-type stars.