Morphology of the interaction between the stream and cool accretion disc in semidetached binaries

it was shown in (Bisikalo et al., 2003) that for realistic parameters of the accretion discs in close binaries (M similar or equal to 10(-12) divided by 10(-7) M circle dot/yr and alpha similar or equal to 10(-1) divided by 10(-2)), the gas temperature in the outer parts of the disc is similar to 10(4) K to similar to 10(6) K. Our previous gas-dynamical studies of mass transfer in close binaries indicate that, for hot discs (with temperatures for the outer parts of the disc of several hundred thousand K), the interaction between the stream from the inner Lagrange point and the disc is shockless. To study the morphology of the interaction between the stream and a cool accretion disc, we carried out three-dimensional modeling of the flow structure in a binary for the case when the gas temperature in the outer parts of the forming disc does not exceed 13 600 K. The flow pattern indicates that the interaction is again shockless. The computations provide evidence that, as is the case for hot,discs, the zone of enhanced energy release (the "hot line") is located beyond the disc, and originates due to the interaction between the circum-disc halo and the stream. It was also shown that during the interaction between the disc and circum-disc halo a sizeable part of matter gets the acceleration in z-direction. This results in formation of a bulge in circum-disc halo with maximum on the phase 0.7.