2004A&A...419..335N -
Astronomy and Astrophysics, volume 419335-343 (2004/5-3)
Wind accretion in binary stars. I. Mass accretion ratio.
NAGAE T., OKA K., MATSUDA T., FUJIWARA H., HACHISU I. and BOFFIN H.M.J.
Abstract (from CDS):
Three-dimensional hydrodynamic calculations are performed in order to investigate mass transfer in a close binary system, in which one component undergoes mass loss through a wind. The mass ratio is assumed to be unity. The radius of the mass-losing star is taken to be about a quarter of the separation between the two stars. Calculations are performed for gases with a ratio of specific heats γ=1.01 and 5/3. Mass loss is assumed to be thermally driven so that the other parameter is the sound speed of the gas on the mass-losing star. Here, we focus our attention on two features: flow patterns and mass accretion ratio, which we define as the ratio of the mass accretion rate onto the companion, {dot}(M)acc, to the mass loss rate from the mass-losing primary star, {dot}(M)loss. We characterize the flow by the mean normal velocity of the wind on the critical Roche surface of the mass-losing star, VR. When VR<0.4AΩ, where A and Ω are the separation between the two stars and the angular orbital frequency of the binary, respectively, we obtain Roche-lobe over-flow (RLOF), while for VR>0.7AΩ we observe wind accretion. We find very complex flow patterns in between these two extreme cases. We derive an empirical formula of the mass accretion ratio as 0.18x10–0.75VR_/AΩ^ in the low velocity regime and 0.05(VR/AΩ)–4 in the high velocity regime.
Abstract Copyright:
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Journal keyword(s):
accretion, accretion disks - hydrodynamics - stars: binaries: general
Simbad objects:
2
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