The Efficiency of Mass Accretion and Disc Structure from the Stellar Wind Mass Transfer in Binary Systems

There have been many research works involving mass transfer in stellar binaries, all of which are limited to certain systems with specific binary parameters. In this work, we use three-dimensional smoothed particle (3D-SPH) simulations to explore the impact of binary mass ratio and wind speed on the fraction of mass transferred to the accreting companion and the structure of accretion discs. We examine all possible cases of binary mass ratios as well as different conditions of wind speed in the vicinity of the accretor. We adhere to thermally driven winds, with sound speed being the main parameter, in which transonic stellar winds expand in the binary medium. We find that mass accretion fraction is close to unity for slow winds. However, fast winds lead to mass accretion fraction of thousandths which agree very well with the Bondi–Hoyle estimates. Mass accretion fraction is found to be the largest when the mass ratio is unity. Our results show that an increase in either sound speed or binary mass ratio leads to decrease in accretion disc size. In most cases, the disc shifts from being circular. These results would allow us to estimate the rate of mass accretion and the structure of accretion discs in any type of stellar binaries.