论文标题
A-Emph {Kepler}旋转调制起源的光谱测试A型星的光度变异性
A spectroscopic test of the rotational modulation origin of periodic \emph{Kepler} photometric variability of A-type stars
论文作者
论文摘要
由\ emph {kepler}和\ emph {tess}任务获得的高精度基于空间的光度法已经揭示了与主序列（MS）A和晚-B型恒星相关的旋转调制的证据。通常，这些物体中的这种可变性归因于通常与强磁场（$ b \ gtrsim100 \，{\ rm g} $）在表面上可见的不均匀表面结构（例如化学点）。据报道，在\ emph {kepler}任务中观察到的所有A型星中，$ \ \ \ ^ obly约为$〜每百分之一。考虑到$ \ lyssim10 $〜每百分之a的a型恒星中的$ \ lyssim10 $〜众所周知，这是令人惊讶的（即它们是ap/bp恒星）。我们提出了对44 A和后B型恒星的光谱监测调查，报告在其\ emph {kepler}光曲线中表现出旋转调制。这项调查的主要目的是测试可变性是通过比较每个恒星的旋转拓宽（$ v \ sin {i} $）与赤道速度（$ v _ {\ rm eq} $）通过比较旋转调制的假设。我们搜索了化学特征和二元同伴，以便深入了解明显旋转调制的起源。我们发现我们的样本中有14颗恒星具有$ v \ sin {i}> v _ {\ rm eq} $和/或具有低质量伴侣，可能对观察到的可变性有助于或负责。我们的结果表明，在所有MS A和后B型恒星中，超过$ 10 $〜 /〜美分可能表现出不均匀的表面结构。但是，发病率可能是$ \ lyssim30 $〜每〜1。
High-precision space-based photometry obtained by the \emph{Kepler} and \emph{TESS} missions has revealed evidence of rotational modulation associated with main sequence (MS) A and late-B type stars. Generally, such variability in these objects is attributed to inhomogeneous surface structures (e.g. chemical spots), which are typically linked to strong magnetic fields ($B\gtrsim100\,{\rm G}$) visible at the surface. It has been reported that $\approx44$~per~cent of all A-type stars observed during the \emph{Kepler} mission exhibit rotationally modulated light curves. This is surprising considering that $\lesssim10$~per~cent of all MS A-type stars are known to be strongly magnetic (i.e. they are Ap/Bp stars). We present a spectroscopic monitoring survey of 44 A and late-B type stars reported to exhibit rotational modulation in their \emph{Kepler} light curves. The primary goal of this survey is to test the hypothesis that the variability is rotational modulation by comparing each star's rotational broadening ($v\sin{i}$) with the equatorial velocities ($v_{\rm eq}$) inferred from the photometric periods. We searched for chemical peculiarities and binary companions in order to provide insight into the origin of the apparent rotational modulation. We find that 14 stars in our sample have $v\sin{i}>v_{\rm eq}$ and/or have low-mass companions that may contribute to or be responsible for the observed variability. Our results suggest that more than $10$~per~cent of all MS A and late-B type stars may exhibit inhomogeneous surface structures; however, the incidence rate is likely $\lesssim30$~per~cent.
