On rapid binary mass transfer – I. Physical model

ABSTRACT In some semidetached binary systems, the donor star may transfer mass to companion at a very high rate. We propose that, sufficiently mass-transfer rates such that accretion disc around becomes geometrically thick (or advection-dominated) near outer radius, large fraction of transferred be lost through Lagrangian (L2) point, as result excessive energy generated by viscous heating cannot efficiently radiated away. A physical model is constructed where L2 mass-loss given requirement remaining material in has Bernoulli number equal potential energy. Our predicts significant exceeding $\mbox{a few}\, 10^{-4}\, {\mathrm{ M}_\odot \, \mathrm{yr}^{-1}}$. An equatorial circumbinary outflow (CBO) formed these systems. Implications for orbital evolution and observational appearance system are discussed. particular, (1) rapid angular momentum loss from tends shrink orbit, hence increase formation rate mergers gravitational-wave sources; (2) photons hot wind reprocessed CBO into longer wavelength emission infrared bands, consistent with Spitzer observations ultra-luminous X-ray sources.