论文标题
接触二进制星星的质量比率分布
Mass-ratio distribution of contact binary stars
论文作者
论文摘要
接触二进制恒星的质量比$ q $由于质量转移，磁制动和热弛豫振荡而演变为小值，直到它越过临界阈值$ q_ \ q_ \ text {min} $。发生这种情况时，二进制会经历潮汐达尔文的不稳定性，从而导致组件的迅速结合并观察到系统的亮度。到目前为止，尚未在足够大的接触二元星星上测量$ Q $的分布，因为单个接触二进制的$ Q $的确定通常需要光谱。但是如前所述，可以从观察到的光曲线振幅的分布中推断出整个接触二进制群体的质量比率分布。我们采用贝叶斯推断，从开普勒剥落的二元目录以及Gaia的数据和有效温度的估计中获得了接触二元候选样本样本。我们为每个候选人分配了近期或早期类型的联系人二进制的概率。总体而言，我们的样本包括大约300个晚期和200个早期型接触二进制候选者。我们假设质量比由带有指数$ b $的电源法描述，并以$ q_ \ text {min} $截止的幅度法对幅度分布进行建模。我们找到$ q_ \ text {min} = 0.087^{+0.024} _ { - 0.015} $，用于延迟型的binteries，周期超过0.3天。对于较短时间的晚期二进制文件，我们发现$ q_ \ text {min} = 0.246^{+0.029} _ { - 0.046} $，但样本很小。对于早期类型的接触二进制恒星，周期短于1天，我们获得$ q_ \ text {min} = 0.030^{+0.018} _ { - 0.022} $。这些结果表明$ q_ \ text {min} $的依赖性对组件的结构，并且与以前的理论预测广泛兼容。我们的方法可以很容易地扩展到来自苔丝和其他空间调查的大量接触二进制样本。
The mass ratio $q$ of a contact binary star evolves due to mass transfer, magnetic braking, and thermal relaxation oscillations to small values until it crosses a critical threshold $q_\text{min}$. When that happens, the binary undergoes the tidal Darwin instability, leading to a rapid coalescence of the components and observable brightening of the system. So far, the distribution of $q$ has not been measured on a sufficiently large population of contact binary stars, because the determination of $q$ for a single contact binary usually requires spectroscopy. But as was shown previously, it is possible to infer the mass-ratio distribution of the entire population of contact binaries from the observed distribution of their light curve amplitudes. Employing Bayesian inference, we obtain a sample of contact binary candidates from the Kepler Eclipsing Binary Catalog combined with data from Gaia and estimates of effective temperatures. We assign to each candidate a probability of being a contact binary of either late or early type. Overall, our sample includes about 300 late-type and 200 early-type contact binary candidates. We model the amplitude distribution assuming that mass ratios are described by a power law with an exponent $b$ and a cut off at $q_\text{min}$. We find $q_\text{min}=0.087^{+0.024}_{-0.015}$ for late-type contact binaries with periods longer than 0.3 days. For late-type binaries with shorter periods, we find $q_\text{min}=0.246^{+0.029}_{-0.046}$, but the sample is small. For early type contact binary stars with periods shorter than 1 day, we obtain $q_\text{min}=0.030^{+0.018}_{-0.022}$. These results indicate a dependence of $q_\text{min}$ on the structure of the components and are broadly compatible with previous theoretical predictions. Our method can be easily extended to large samples of contact binaries from TESS and other space-based surveys.
