论文标题
猎户座星云群中的HST天文学：低质量逃亡者的人口普查
HST astrometry in the Orion Nebula Cluster: census of low-mass runaways
论文作者
论文摘要
我们介绍了基于Hubble Space望远镜（HST）ACS/WFC摄像头的国库计划观察，介绍了猎户座星云集群（ONC）中高精度适当动作的目录。 Our catalog contains 2,454 objects in the magnitude range of $14.2<m_{\rm F775W}<24.7$, thus probing the stellar masses of the ONC from $\sim$0.4 $M_\odot$ down to $\sim$0.02 $M_\odot$ over an area of $\sim$550 arcmin$^2$.我们为ONC提供了许多内部速度分散估计，这表明对恒星位置和质量的依赖性较弱。与已发布的速度分散估计值有很好的一致性，尽管几乎所有（包括我们的$σ_{v，x} = 0.94 $和$σ_{v，y} = 1.25 $ MAS yr $^{ - 1} $）可能会因重叠的年轻的Orion A. Orion A. new new new new new new new unciad而偏向于偏见，所有质量都小于$ \ sim $ 1 $ m_ \ odot $。已知候选逃亡者的总人口普查是10，这是有史以来在任何银河系开放式明星集群中发现的最大样本之一。令人惊讶的是，它们都没有超过20 km S $^{ - 1} $的切向速度。如果它们中的大多数确实起源于ONC，则可能会在非常年轻的星团中重新检查动态过程。看来ONC的质量功能并未受到丢失的逃亡者的显着影响。
We present a catalog of high-precision proper motions in the Orion Nebula Cluster (ONC), based on Treasury Program observations with the Hubble Space Telescope's (HST) ACS/WFC camera. Our catalog contains 2,454 objects in the magnitude range of $14.2<m_{\rm F775W}<24.7$, thus probing the stellar masses of the ONC from $\sim$0.4 $M_\odot$ down to $\sim$0.02 $M_\odot$ over an area of $\sim$550 arcmin$^2$. We provide a number of internal velocity dispersion estimates for the ONC that indicate a weak dependence on the stellar location and mass. There is good agreement with the published velocity dispersion estimates, although nearly all of them (including ours at $σ_{v,x}=0.94$ and $σ_{v,y}=1.25$ mas yr$^{-1}$) might be biased by the overlapping young stellar populations of Orion A. We identified 4 new ONC candidate runaways based on HST and the Gaia DR2 data, all with masses less than $\sim$1 $M_\odot$. The total census of known candidate runaway sources is 10 -- one of the largest samples ever found in any Milky Way open star cluster. Surprisingly, none of them has the tangential velocity exceeding 20 km s$^{-1}$. If most of them indeed originated in the ONC, it may compel re-examination of dynamical processes in very young star clusters. It appears that the mass function of the ONC is not significantly affected by the lost runaways.
