著者

長江 滝三 松田 卓也 藤原 秀和 蜂巣 泉 Boffin H. M. J.

出版者

日本流体力学会

雑誌

日本流体力学会年会講演論文集 (ISSN:13428004)

巻号頁・発行日

vol.2002, pp.124-125, 2002-07-23

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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 of the two stars. Calculations are performed for gases with a ratio of specific heatsγ=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 to two features : flow patterns and mass accretion ratio, which we define as the ratio of the mass accretion rate onto the companion, M_<acc>, to the mass loss rate from the mass-losing primary star, M_<loss>. We characterize flows by the mean normal velocity of wind on the critical Roche surface of the mass-losing star, V_R. When V_R < 0.4AΩ, where A and Ω are the separation of two stars and the rotational frequency of the binary, respectively, we obtain Roche-lobe over-flow (RLOF), while for V_R > 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 0.45×10^<-1.8V_R/AΩ> in the low velocity regime and 5.0×10^<-3> (V_R/AΩ)^<-4> in the high velocity regime.