Rapid Binary Mass Transfer

We propose that, at sufficiently high mass transfer rate (> a few times 10^-4 Msun/yr) such that the accretion disk around the accretor becomes geometrically thick (or advection-dominated) near the outer radius, a large fraction of the transferred mass will be lost through the outer Lagrangian (L2) point. A physical model is constructed where the L2 mass loss fraction is given by the requirement that the remaining material in the disk has Bernoulli number equal to the L2 potential energy. We discuss the implications on the orbital evolution and observational appearance of the binary system.