A Complete Survey of Case A Binary Evolution with Comparison to Observed Algol-type Systems
A Complete Survey of Case A Binary Evolution with Comparison to Observed Algol-type Systems
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DOI：
10.1086/320560
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发表时间：
2000-09
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通讯作者：
Cailin A. Nelson Peter P. Eggleton
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作者：
Cailin A. Nelson Peter P. Eggleton
我们进行了比较观察到的Algol型二进制与计算的情况下二进制演化轨道库。该库由5500个具有不同初始质量M10、质量比q 0和周期P0值的双星轨道组成，旨在对范围为-0.10 ≤ log M10 ≤ 1.7的A类双星的相空间进行采样。每一个二进制的演变使用一个标准的代码与假设，总质量和轨道角动量守恒。这个代码遵循两颗恒星的演化，直到发生接触或反向质量转移。由此产生的二进制轨迹显示了丰富多样的行为，我们将其分为情况A和情况B的几个子类。我们提出了这种分类的结果，最终的质量比，并在罗氏瓣溢出每个二元系统所花费的时间的分数。我们创建这个库的保守假设预计适用于广泛的二进制文件，其中两个组件的光谱范围为G 0到B1和光度类别III到V。我们收集了一个相对确定的列表，观察到的热Algol型二进制文件符合这一标准，以及一个较冷的Algol型二进制文件列表，我们预计会有显著的发电机驱动的质量损失和角动量损失。我们使用χ2最小化程序将每个观察到的二进制文件拟合到我们的轨迹库中。我们发现，热的阿尔戈显示整体可接受的χ2，证实了保守的假设，而冷的阿尔戈显示更不可接受的χ2，这表明需要更多的自由参数，如质量和角动量损失。
We undertake a comparison of observed Algol-type binaries with a library of computed Case A binary evolution tracks. The library consists of 5500 binary tracks with various values of initial primary mass M10, mass ratio q0, and period P0, designed to sample the phase-space of Case A binaries in the range -0.10 ≤ log M10 ≤ 1.7. Each binary is evolved using a standard code with the assumption that both total mass and orbital angular momentum are conserved. This code follows the evolution of both stars to the point where contact or reverse mass transfer occurs. The resulting binary tracks show a rich variety of behavior that we sort into several subclasses of case A and case B. We present the results of this classification, the final mass ratio, and the fraction of time spent in Roche Lobe overflow for each binary system. The conservative assumption under which we created this library is expected to hold for a broad range of binaries, where both components have spectra in the range G0 to B1 and luminosity classes III to V. We gather a list of relatively well-determined, observed hot Algol-type binaries meeting this criterion, as well as a list of cooler Algol-type binaries, for which we expect significant dynamo-driven mass loss and angular momentum loss. We fit each observed binary to our library of tracks using a χ2-minimizing procedure. We find that the hot Algols display overall acceptable χ2, confirming the conservative assumption, while the cool Algols show much less acceptable χ2, suggesting the need for more free parameters, such as mass and angular momentum loss.