潮汐效应、系统自转效应对双星物质交换过程的影响

The Effects of Tide and Rotation on the Mass Exchange Process in Binary Systems

现今双星演化理论中，以子星的半径等于临界洛希瓣半径，作为双星中发生物质交换过程的判据，仅仅是一个为了将三维计算简化为一维计算而引入的近似判据．它在理论上是不严格的．本文给出了一个理论严格而又能一维计算的判据．并用新的判据和用子星半径等于临界洛希瓣半径的判据，对一个由９Ｍ和６Ｍ恒星组成的双星系统，进行了情况Ａ的演化计算（即物质交换过程发生在主星中心氢燃烧阶段）．结果证明，用新的判据时，双星中发生物质交换过程的起始时间提前，快速物质交换过程变短，平均物质交换率增大，但慢速物质交换过程变长．在物质交换过程结束时，主星和次星的质量、双星系统的轨道周期以及主星在赫罗图中的位置，都与采用子星半径等于相应洛希瓣半径作为判据的计算结果明显不同．这说明，发生物质交换过程的判据是否严格，对于双星演化的影响是不可忽略的．

he criterion for the onset of mass exchange when the radius of a component starreaches its Roche lobe is only approximate, introduced to make the calculation one-dimensional.We propose a more strict criterion which still leaves the problem one-dimensional. We examine the Case A evolution of a 9 M + 6 M binary system according to both the strictand approximate criteria. The results show that, with the strict criterion, the mass exchangeprocess starts earlier, the fast mass exchange process becomes shorter with a larger averagemass exchange rate, and the slow mass exchange process stops later, leading to differentcomponent masses, different orbital period and different positions on the HR diagram.