Photometric Stellar Variability in the Galactic Center
Photometric Stellar Variability in the Galactic Center
复制标题
银河系中心的光度恒星变率
DOI：
10.1086/512062
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
M. Morris
中科院分区：
文献类型：
--
作者：
M. Rafelski;A. Ghez;S. Hornstein;J. Lu;M. Morris
我们报告了在过去的10年里，利用W. m . Keck I 10米望远镜上的散斑成像技术，对银河系中心5“× 5”进行的衍射限制、光度变异性研究的结果。在我们的限定星等mK < 16等范围内，我们发现131颗被监测的恒星中至少有15颗K[2.2 μm]波段的变星。我们样本中唯一的周期源是先前确定的变量IRS 16SW，我们测量到它的轨道周期为19.448±0.002天。与最近的结果相反，我们在IRS 16SW上的数据显示出不对称的相位光曲线，其下降时间比上升时间陡峭得多，这可能是由于恒星在其轨道上的接近引起的潮汐变形。我们还根据其在几年时间尺度上的光度变化确定了一个可能的风碰撞双星（IRS 29N），这可能是由于间歇性的尘埃产生。在我们的样本中，四个发光蓝变量（LBV）候选体都没有表现出光度的显著增加或减少。然而，我们的时间底线太短，不能排除它们是lbv。在剩余的变星中，大多数是早期型恒星，其中三颗可能是由于视线消光变化而变化的。对于我们视野中心的七颗OB恒星，它们有明确的三维轨道，我们没有看到耀斑或光线变暗的证据，这限制了超大质量黑洞Sgr a *周围存在寒冷、几何上薄、不活跃的吸积盘的可能性。
We report the results of a diffraction-limited, photometric variability study of the central 5′′ × 5′′ of the Galaxy conducted over the past 10 years using speckle imaging techniques on the W. M. Keck I 10 m telescope. Within our limiting magnitude of mK < 16 mag for images made from a single night of data, we find a minimum of 15 K[2.2 μm]-band variable stars out of 131 monitored stars. The only periodic source in our sample is the previously identified variable IRS 16SW, for which we measure an orbital period of 19.448 ± 0.002 days. In contrast to recent results, our data on IRS 16SW show an asymmetric phased light curve with a much steeper fall time than rise time, which may be due to tidal deformations caused by the proximity of the stars in their orbits. We also identify a possible wind colliding binary (IRS 29N) based on its photometric variation over a few year timescale, which is likely due to episodic dust production. None of the four luminous blue variable (LBV) candidates in our sample show the characteristic large increase or decrease in luminosity. However, our time baseline is too short to rule them out as LBVs. Among the remaining variable stars, the majority are early-type stars, and three are possibly variable due to line-of-sight extinction variations. For the seven OB stars at the center of our field of view that have well-determined three-dimensional orbits, we see no evidence of flares or dimming of their light, which limits the possibility of a cold, geometrically thin, inactive accretion disk around the supermassive black hole, Sgr A*.