论文标题
视觉二进制的自旋轨道对齐
The spin-orbit alignment of visual binaries
论文作者
论文摘要
恒星自旋轴与恒星或行星伴侣的轨道平面之间的角度对这种系统的形成和演变具有重要意义。 Hale（1994）的一项研究发现，具有分离$ a <30 $ au的二进制文件优先对齐，而较宽的轨道上的二进制文件经常被错误对准。我们旨在通过使用独立衍生的恒星参数和贝叶斯形式主义重新旋转旋转周期来重现视觉二进制的样本，以测试Hale（1994）结果的鲁棒性。我们的分析基于Hale（1994）的数据以及来自Hertzsprung Song望远镜的新近获得的光谱数据的组合，并结合了Gaia DR2和Washington Double Star Catalog的星体数据。我们结合了恒星半径和旋转周期的测量值，以获得恒星旋转速度$ v $。旋转速度$ v $与预计旋转速度的测量$ v \ sin i $相结合，以得出恒星倾斜角$ i $的后验概率分布。我们通过将恒星倾斜角与天体轨道倾斜角进行比较，确定了视线的投影旋转角度。我们发现，可用数据的精度不足以推断出视觉二进制的自旋轨道对齐。数据在所有轨道分离中都与对齐和未对准同样兼容。我们得出的结论是，先前报道的趋势是，分离$ a <30 $ au的二进制优先是虚假的。视觉二进制文件的自旋轨道对齐分布不受约束。基于模拟观察结果，我们预测，在$ v \ sin i $，旋转期和轨道倾斜度中，对于对视觉二进制的旋转轨道排列进行了强大的统计推断，将很难达到足够的精度。
The angle between the stellar spin-axis and the orbital plane of a stellar or planetary companion has important implications for the formation and evolution of such systems. A study by Hale (1994) found that binaries with separations $a < 30$ au are preferentially aligned while binaries on wider orbits are frequently misaligned. We aim to test the robustness of the Hale (1994) results by reanalysing the sample of visual binaries with measured rotation periods using independently derived stellar parameters and a Bayesian formalism. Our analysis is based on a combination of data from Hale (1994) and newly obtained spectroscopic data from the Hertzsprung SONG telescope, combined with astrometric data from Gaia DR2 and the Washington Double Star Catalog. We combine measurements of stellar radii and rotation periods to obtain stellar rotational velocities $v$. Rotational velocities $v$ are combined with measurements of projected rotational velocities $v\sin i$ to derive posterior probability distributions of stellar inclination angles $i$. We determine line-of-sight projected spin-orbit angles by comparing stellar inclination angles with astrometric orbital inclination angles. We find that the precision of the available data is insufficient to make inferences about the spin-orbit alignment of visual binaries. The data are equally compatible with alignment and misalignment at all orbital separations. We conclude that the previously reported trend that binaries with separations $a < 30$ au are preferentially aligned is spurious. The spin-orbit alignment distribution of visual binaries is unconstrained. Based on simulated observations, we predict that it will be difficult to reach the sufficient precision in $v\sin i$, rotation periods, and orbital inclination required to make robust statistical inferences about the spin-orbit alignment of visual binaries.
