The evolution of W Ursae Majoris systems
The evolution of W Ursae Majoris systems
复制标题
DOI：
10.1093/mnras/179.3.359
复制
发表时间：
1977-07
影响因子：
4.8
通讯作者：
J. A. Robertson;P. Eggleton
中科院分区：
文献类型：
--
作者：
J. A. Robertson;P. Eggleton
为了了解W UMa双星的结构，研究了近接触和近接触双星模型的演化。计算的总系统质量为1.8M，并为各种轨道角动量和程度的核演化。循环行为的热时标，交替接触和半分离的阶段，通常被发现，虽然在某些情况下，获得一个稳定的等质量系统。核演化和较低的角动量都导致周期集中在更极端的质量比上，接触时间的比例似乎大大增加。一个演化的模型在表面上稳定的浅接触状态，q ~ 0.4。我们认为，这可能代表一个相当典型的A型W UMa系统。循环模型的缺点是，在半分离阶段，系统将被期望表现出EB型的光变曲线，必须承认，（到目前为止）没有短周期（P = 0，4天）EB双星已经观察到。我们在文中给出了相信这一困难并非不可克服的理由。
In an attempt to understand the structure of W UMa binaries, the evolution of close binary models in and near contact has been investigated. Calculations have been performed for a total system mass of 1.8M⊙, and for various orbital angular momenta and degrees of nuclear evolution. Cyclic behaviour on a thermal timescale, with alternating contact and semi-detached phases, is generally found although in some circumstances a stable equal-mass system is obtained. Both nuclear evolution and lower angular momentum cause the cycles to be centred on more extreme mass ratios, and the fraction of time spent in contact appears to increase considerably. One evolved model settles in an apparently stable state of shallow contact withq~ 0.4. We suggest that this may represent a fairly typical A-type W UMa system. The drawback of the cyclic models is that during the semi-detached phase the systems would be expected to exhibit EB-type light curves, and it must be admitted that (so far) no short-period (P≲0, four days) EB binaries have been observed. We give in the text reasons for believing that this difficulty is not insurmountable.