A radiation-driven disc wind model for massive young stellar objects

A radiation-driven disc wind model is proposed that offers great promise of explaining the extreme mass-loss signatures of massive young stellar objects (the BN-type objects and more luminous Herbig Be stars). It is argued that the dense low-velocity winds associated with young late O/early B stars would be the consequence of continuing optically thick accretion on to them. The launch of outflow from a Keplerian disc allows wind speeds of similar to 200 km s(-1) that are substantially less than the escape speed from the stellar surface. The star itself is not required to be a rapid rotator. Disc irradiation is taken into account in the hydrodynamical calculation presented, and identified as an important issue both observationally and from the dynamical point of view.