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arXiv 0804.2294astro-ph
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巨星向主序星伴星的质量转移及其对长轨道周期蓝离散星的贡献

Mass transfer from a giant star to a main sequence companion and its contribution to long-orbital-period blue stragglers

Xuefei Chen, Zhanwen Han

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16 pages, 17 figures. accepted by MNRAS
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摘要：

双星总体综合表明，从巨星到主序星伴星的质量转移可能是一些观测到的长轨道周期蓝离散星的原因。然而，很少有人注意到{ \bf支付给这个蓝离散形成的情况}，动力学不稳定性经常发生时，质量供体是一个巨星。本文用详细的演化计算方法研究了从巨星到MS伴星动态稳定质量转移的临界质量比$q_{\rm c}$。结果表明，一个更成熟的恒星通常是不稳定的洛希叶溢出。同时，$q_{\rm c}$随质量和角动量{ \bf损失}的增加几乎呈线性增加，但对恒星风的依赖性很小.为了方便使用的结果，我们给出了一个拟合的$q_{\rm c}$的恒星半径在洛希瓣溢出的开始和洛希瓣溢出期间的传质效率的函数。为了研究巨星和MS星之间的质量转移形成的蓝离散星，我们用不同的$q_{\rm c}$进行了蒙特卡罗模拟。模拟结果表明，某些质量施主在第一巨分支上的双星可能对蓝离散星有贡献，而对以前的$q_{\rm c}$没有贡献，这与本文得到的$q_{\rm c}$有关.与此同时，从我们的$q_{\rm c}$，蓝色离散星之间的质量转移的AGB星和MS的同伴可能是更多的，并有一个更广泛的轨道周期比那些从其他$q_{\rm c}$。

英文摘要：

Binary population synthesis shows that mass transfer from a giant star to a main-sequence (MS) companion may account for some observed long-orbital period blue stragglers. However, little attention {\bf is paid to this blue straggler formation scenario} as dynamical instability often happens when the mass donor is a giant star. In this paper, we have studied the critical mass ratio, $q_{\rm c}$, for dynamically stable mass transfer from a giant star to a MS companion using detailed evolution calculations. The results show that a more evolved star is generally less stable for Roche lobe overflow. Meanwhile, $q_{\rm c}$ almost linearly increases with the amount of the mass and angular momentum {\bf lost} during mass transfer, but has little dependance on stellar wind. To conveniently use the result, we give a fit of $q_{\rm c}$ as a function of the stellar radius at the onset of Roche lobe overflow and of the mass transfer efficiency during the Roche lobe overflow. To examine the formation of blue stragglers from mass transfer between giants and MS stars, we have performed Monte Carlo simulations with various $q_{\rm c}$. {\bf The simulations show that some binaries with the mass donor on the first giant branch may contribute to blue stragglers with $q_{\rm c}$ obtained in this paper but will not from previous $q_{\rm c}$. Meanwhile, from our $q_{\rm c}$, blue stragglers from the mass transfer between an AGB star and a MS companion may be more numerous and have a wider range of orbital periods than those from the other $q_{\rm c}$.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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