论文标题

从猎户座星云群中寻找逃亡者

Hunting for Runaways from the Orion Nebula Cluster

论文作者

Farias, Juan P., Tan, Jonathan C., Eyer, Laurent

论文摘要

我们使用Gaia Dr2来寻找猎户座星云群(ONC)的失控恒星。我们搜索一个区域,该区域在ONC周围延伸45°,然后搜索1 kpc,以找到与群集在最后一个〜10 MYR中与群集重叠的来源。我们发现约有17,000名失控/旅行者候选人满足了这个2D追溯条件。预计其中大多数是污染物,例如,由不同距离的恒星的银河流动运动引起。因此,我们检查了六项进一步的测试,以帮助识别实际逃亡者,即:(1)具有基于Gaia光学光度法的年轻恒星对象(YSO)颜色和幅度; (2)与基于2个质量和明智的光度法的IR与YSO一致; (3)具有高度的光学变异性; (4)在群集半径半径内的最接近方法距离; (5)具有避免主要银河流污染区的弹出方向; (6)具有合理幅度的3D重叠的必需径向速度(RV)(或者,对于具有测量RV的7%的候选者,满足3D追溯)。 13个来源(以前没有称为猎户座成员)通过了所有这些测试,而另外十二个则是同样有希望的,除了它们位于主要的银河流污染区。在这25个弹射候选者中,有测得的RVS的十个通过最严格的3D追溯条件。我们介绍了失控/走路候选人的完整列表,估计了从ONC弹出的高速群体,并通过与数值模拟进行比较,讨论了其对群集形成理论的影响。

We use Gaia DR2 to hunt for runaway stars from the Orion Nebula Cluster (ONC). We search a region extending 45° around the ONC and out to 1 kpc to find sources that overlapped in angular position with the cluster in the last ~10 Myr. We find ~17,000 runaway/walkaway candidates satisfy this 2D traceback condition. Most of these are expected to be contaminants, e.g., caused by Galactic streaming motions of stars at different distances. We thus examine six further tests to help identify real runaways, namely: (1) possessing young stellar object (YSO) colors and magnitudes based on Gaia optical photometry; (2) having IR excess consistent with YSOs based on 2MASS and WISE photometry; (3) having a high degree of optical variability; (4) having closest approach distances well constrained to within the cluster half-mass radius; (5) having ejection directions that avoid the main Galactic streaming contamination zone; and (6) having a required radial velocity (RV) for 3D overlap of reasonable magnitude (or, for the 7% of candidates with measured RVs, satisfying 3D traceback). Thirteen sources, not previously noted as Orion members, pass all these tests, while another twelve are similarly promising, except they are in the main Galactic streaming contamination zone. Among these 25 ejection candidates, ten with measured RVs pass the most restrictive 3D traceback condition. We present full lists of runaway/walkaway candidates, estimate the high-velocity population ejected from the ONC and discuss its implications for cluster formation theories via comparison with numerical simulations.

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