Be星的亚毫弧秒精度光谱天体测量
Sub-milliarcsecond precision spectro-astrometry of Be stars
摘要：
Be星周围的盘的起源仍然不清楚。进一步的进展需要适当的参数化的结构，空间和运动学。这是具有挑战性的，因为磁盘非常小。在这里，我们评估一种新的方法是否能够提供这些数据。我们获得了光谱天体测量周围的Pa β线的两个明亮的Be星，α Col和zeta Tau，寻找磁盘签名。该数据的质心位置的像素到像素精度为0.3。0.4毫角秒是迄今为止最精确的此类数据。数据中存在0.85 mas水平的伪影，但这些伪影很容易识别，因为它们在我们的冗余数据集中不可重复。这确实说明了需要采取多个数据，以避免虚假的检测。的数据进行了比较，由于旋转磁盘周围的恒星的光谱天体测量签名的简单模型模拟。如果旋转开普勒，我们发现的盘半径上限对应于几十个恒星半径的盘大小。这是非常接近的观测测量和理论上预期的磁盘大小，因此，本文表明，光谱天体测量，其中我们提出的第一个这样的尝试，有可能解决磁盘周围的Be星。
英文摘要：
The origin of the disks around Be stars is still not known. Further progress requires a proper parametrization of their structure, both spatially and kinematically. This is challenging as the disks are very small. Here we assess whether a novel method is capable of providing these data. We obtained spectro astrometry around the Pa beta line of two bright Be stars, alpha Col and zeta Tau, to search for disk signatures. The data, with a pixel to pixel precision of the centroid position of 0.3..0.4 milliarcsecond is the most accurate such data to date. Artefacts at the 0.85 mas level are present in the data, but these are readily identified as they were non-repeatable in our redundant datasets. This does illustrate the need of taking multiple data to avoid spurious detections. The data are compared with simple model simulations of the spectro astrometric signatures due to rotating disks around Be stars. The upper limits we find for the disk radii correspond to disk sizes of a few dozen stellar radii if they rotate Keplerian. This is very close to observationally measured and theoretically expected disk sizes, and this paper therefore demonstrates that spectro-astrometry, of which we present the first such attempt, has the potential to resolve the disks around Be stars.
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