A Simultaneous Optical and X-Ray Variability Study of the Orion Nebula Cluster. I. Incidence of Time-correlated X-Ray/Optical Variations
A Simultaneous Optical and X-Ray Variability Study of the Orion Nebula Cluster. I. Incidence of Time-correlated X-Ray/Optical Variations
复制标题
猎户座星云团的同时光学和 X 射线变异性研究。
DOI：
10.1086/506422
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
E. Flaccomio
中科院分区：
文献类型：
--
作者：
K. Stassun;M. van den Berg;E. Feigelson;E. Flaccomio
我们提供了一个猎户座星云星团的BVRI时间序列测光数据库，该数据库由两个位于不同经度的地面望远镜获得，以提供对该星系团13天的Chandra观测的同时覆盖。由此产生的大约800颗主序前恒星的同时光学和X射线光曲线数据库，以数百倍的比例代表了迄今为止对年轻恒星进行的最大规模的天气学、多波长制度、时间序列研究。该数据库将详细分析经前综合征恒星的光学和X射线可变性之间的关系，目的是阐明经前综合征X射线产生的起源。在第一篇文章中，我们介绍了光学观测，描述了X射线/光学联合数据库，并分析了光学和X射线光曲线的时间相关变异性。我们确定了40颗恒星(占我们研究样本的5%)，它们可能具有与时间相关的光学和X射线可变性。发现了正和负时间关联的例子，可能代表了X射线耀斑和持续的日冕特征，与表面的冷和热斑点(即磁活动区和吸积激波)有关。我们还发现了两个可能的“白光”耀斑与X射线耀斑重合的例子；这两个例子可能对应于类似太阳耀斑的脉冲加热阶段。然而，尽管很有趣，但这些都是不寻常的案例。更广泛地说，我们发现很少有证据表明经前综合征恒星的光学可变性和X射线可变性之间存在直接的因果联系。我们的发现不支持吸积是经前综合征恒星产生X射线的主要驱动力的结论。
We present a database of BVRI time-series photometry of the Orion Nebula Cluster obtained with two ground-based telescopes at different longitudes to provide simultaneous coverage with the 13 day Chandra observation of the cluster. The resulting database of simultaneous optical and X-ray light curves for some 800 pre-main-sequence (PMS) stars represents, by a factor of hundreds, the largest synoptic, multi-wavelength-regime, time-series study of young stars to date. This database will permit detailed analyses of the relationship between optical and X-ray variability among a statistically significant ensemble of PMS stars, with the goal of elucidating the origins of PMS X-ray production. In this first paper, we present the optical observations, describe the combined X-ray/optical database, and perform an analysis of time-correlated variability in the optical and X-ray light curves. We identify 40 stars (representing 5% of our study sample) with possible time-correlated optical and X-ray variability. Examples of both positive and negative time correlations are found, possibly representing X-ray flares and persistent coronal features associated with both cool and hot surface spots (i.e., magnetically active regions and accretion shocks). We also find two possible examples of "white-light" flares coincident with X-ray flares; these may correspond to the impulsive heating phase in solar-analog flares. However, although interesting, these represent unusual cases. More generally, we find very little evidence to suggest a direct causal link between the sources of optical and X-ray variability in PMS stars. The conclusion that accretion is a primary driver of X-ray production in PMS stars is not supported by our findings.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell