| A Model for Contact Binary Systems |
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| 作者姓名： | Han-Feng Song Run-Qian Huang Shao-Lan Bi |
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| 作者单位： | Han-Feng Song1，2，Run-Qian Huang1 and Shao-Lan Bi1 1 National Astronomical Observatories/Yunnan Observatory，Chinese Academy of Sciences，Kunming 650011; 2 Graduate School of Chinese Academy of Sciences，Beijing 100049 |
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| 摘 要： | A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understand-ing that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rota-tion and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M and one 5M star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal.
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| 关 键 词： | stars: binaries — stars: evolution |
| 修稿时间： | 2006-07-10 |
A Model for Contact Binary Systems |
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| Han-Feng Song Run-Qian Huang Shao-Lan Bi.A Model for Contact Binary Systems[J].Chinese Journal of Astronomy and Astrophysics,2007,7(4):539-550. |
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| Authors: | Han-Feng Song Run-Qian Huang Shao-Lan Bi |
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| Abstract: | A model for contact binary systems is presented, which incorporates the following special features: a) The energy exchange between the components is based on the understand-ing that the energy exchange is due to the release of potential, kinetic and thermal energies of the exchanged mass. b) A special form of mass and angular momentum loss occurring in contact binaries is losses via the outer Lagrangian point. c) The effects of spin, orbital rota-tion and tidal action on the stellar structure as well as the effect of meridian circulation on the mixing of the chemical elements are considered. d) The model is valid not only for low-mass contact binaries but also for high-mass contact binaries. For illustration, we used the model to trace the evolution of a massive binary system consisting of one 12M and one 5M star. The result shows that the start and end of the contact stage fall within the semi-detached phase during which the primary continually transfers mass to the secondary. The time span of the contact stage is short and the mass transfer rate is very large. Therefore, the contact stage can be regarded as a special part of the semi-detached phase with a large mass transfer rate. Both mass loss through the outer Lagrangian point and oscillation between contact and semi-contact states can occur during the contact phase, and the effective temperatures of the primary and the secondary are almost equal. |
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| Keywords: | stars: binaries - stars: evolution |
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