论文标题
观察到的二元种群反映了银河系历史。解释宽热的二进制元素的轨道周期比率关系
Observed binary populations reflect the Galactic history. Explaining the orbital period-mass ratio relation in wide hot subdwarf binaries
论文作者
论文摘要
具有主要序列伴侣的宽热细分B（SDB）二进制文件是来自进化的红色巨人的稳定传质的结果。这些二进制文件的轨道在轨道周期和质量比之间显示出很强的相关性。到目前为止，这种相关性的起源一直缺乏结论性的解释。我们的目标是找到一个可以解释观察到的相关性的二元进化模型。进化的红色巨人的半径，因此产生的轨道周期很大程度上取决于它们的金属性。我们使用了二元恒星进化代码MESA进行了一项较小但统计学意义的二元种群合成研究。我们已经使用了标准模型来实现二元质量损失和标准的银河金属性历史记录。根据观测值中使用的标准选择所得的SDB，然后与观察到的种群进行比较。我们已经与观察到的时期质量比相关性达到了极好的匹配，而没有明确调整任何参数。此外，我们的模型与观察到的时期 - 金属性相关性产生了很好的匹配。我们预测了几种新的相关性，这些相关性将观察到的SDB二进制文件与其祖细胞联系起来，并在该时期，金属性和核心质量之间的相关性与少量的年轻低质量He He He Dwarfs之间存在相关性。我们还预测，SDB二进制文件具有独特的轨道特性，具体取决于它们在凸起，薄还是厚的圆盘还是光晕中形成。我们首次证明了银河系的金属性历史如何印在观察到的质量后转移二进制物的性质中。我们表明，银河化学演化是包含至少一个进化的低质量（MI <1.6 MSOL）组件的相互作用系统二元人群研究的重要因素。最后，我们提供了从低质量红色巨人到主要序列恒星的观察支持模型。
Wide hot subdwarf B (sdB) binaries with main-sequence companions are outcomes of stable mass transfer from evolved red giants. The orbits of these binaries show a strong correlation between their orbital periods and mass ratios. The origins of this correlation have, so far, been lacking a conclusive explanation. We aim to find a binary evolution model which can explain the observed correlation. Radii of evolved red giants, and hence the resulting orbital periods, strongly depend on their metallicity. We have performed a small but statistically significant binary population synthesis study with the binary stellar evolution code MESA. We have used a standard model for binary mass loss and a standard Galactic metallicity history. The resulting sdBs were selected based on the same criteria as used in observations and then compared with the observed population. We have achieved an excellent match to the observed period - mass ratio correlation without explicitly fine-tuning any parameters. Furthermore, our models produce a good match to the observed period - metallicity correlation. We predict several new correlations which link the observed sdB binaries to their progenitors, and a correlation between the period, metallicity and core mass for subdwarfs and young low-mass He white dwarfs. We also predict that sdB binaries have distinct orbital properties depending on whether they formed in the bulge, thin or thick disc, or the halo. We demonstrate, for the first time, how the metallicity history of the Milky Way is imprinted in the properties of the observed post-mass transfer binaries. We show that Galactic chemical evolution is an important factor in binary population studies of interacting systems containing at least one evolved low-mass (Mi < 1.6 Msol) component. Finally, we provide an observationally supported model of mass transfer from low-mass red giants onto main-sequence stars.
