3D Numerical Simulation of Mass Transfer in Semidetached Binaries

The results of numerical simulation of mass transfer in semidetached non-magnetic binaries are presented. We investigate the morphology of gaseous flows on the base of three-dimensional gasdynamical calculations of interacting binaries of different types (cataclysmic variables and low-mass X-ray binaries). It was found out that taking into account of the common envelope leads to significant changes in the stream-disk morphology. In particular, the obtained steady-state self-consistent solutions for non-magnetic semidetached binaries show the absence of impact between the gas stream from the inner Lagrangian point and the forming accretion disk. The stream deviates under the action of gas of common envelope, and does not cause shock perturbation of the disk edge (traditional 'hot spot'). At the same time, the gas of common envelope interacts with the stream and causes the formation of extended shock wave, located on the stream boundary. We discuss the implication of considered gasdynamical model without 'hot spot' (but with shock wave) for interpretation of observations. The comparison of synthetic light curves with observations proves the validity of discussed gasdynamical model without 'hot spot'. We have also considered the influence of common envelope on the mass transfer rate in semidetached binaries. The obtained features of flow structure in the vicinity of L₁ show that the gas of common envelope plays an important role in the flow dynamics, and that it leads to significant (in order of magnitude) increasing of mass transfer rate. The most important input to this increasing is defined by stripping of the mass-loosing star atmosphere by interstellar gas flows.