论文标题
开放式群集的早期型失控星的起源
The origin of early-type runaway stars from open clusters
论文作者
论文摘要
失控的星星从银河磁盘中的出生地弹出，一些年轻的B型逃亡者发现飞机以超越逃生速度的速度行驶的飞机几十千座。年轻的开放式群集可能是起源的地方，弹射可能是通过N体相互作用或二进制超新星爆炸。 GAIA天文统计的优异品质为研究年轻失控星的运动学的道路提供了高度的精度，以至于可以独特地确定开放式恒星簇中的原始位置。我们开发了一种有效的最小化方法来计算两个或多个对象是否可能来自同一位置，我们根据Orion Runaways的样本进行了测试。然后，我们的拟合过程用于计算已知的失控恒星的轨迹，在该恒星中我们使用了GAIA数据并更新了径向速度。我们发现，只有一半的样本可以归类为逃亡者，而其他样本则可以归类为逃亡者。后者的大多数恒星原来是二进制的。我们根据其轨迹确定了父簇的逃亡簇，然后使用星星的年龄和飞行时间来研究弹出率是否可能是由于二进制超新星或由于动态弹出的原因。特别是，我们表明，经典的Runaways Ae Aurigae和$ $ $ $ columbae可能不是起源的，$μ$ columbae较早地从Collinder 69中射出了ONC附近的群集。研究的第二个样本包括光环中的一组遥远的B恒星，通过定量光谱分析仔细研究了该样本。我们能够识别至少四颗恒星的候选母体群集，包括Hyper-Runaway候选HIP 60350。弹出事件必须非常暴力，以速度高达150至400 km/s的速度弹出恒星。
Runaway stars are ejected from their place of birth in the Galactic disk, with some young B-type runaways found several tens of kiloparsecs from the plane traveling at speeds beyond the escape velocity. Young open clusters are a likely place of origin, and ejection may be either through N-body interactions or in binary supernova explosions. The excellent quality of Gaia astrometry opens up the path to study the kinematics of young runaway stars to such a high precision that the place of origin in open stellar clusters can be identified uniquely. We developed an efficient minimization method to calculate whether two or more objects may come from the same place, which we tested against samples of Orion runaways. Our fitting procedure was then used to calculate trajectories for known runaway stars where we used Gaia data and updated radial velocities. We found that only half of the sample could be classified as runaways while the others were walkaway stars. Most of the latter stars turned out to be binaries. We identified parent clusters for runaways based on their trajectories and then used cluster age and flight time of the stars to investigate whether the ejection was likely due to a binary supernova or due to a dynamical ejection. In particular, we show that the classical runaways AE Aurigae and $μ$ Columbae might not have originated together, with $μ$ Columbae having an earlier ejection from Collinder 69, a cluster near the ONC. The second sample investigated comprises a set of distant runaway B stars in the halo which have been studied carefully by quantitative spectral analyses. We are able to identify candidate parent clusters for at least four stars including the hyper-runaway candidate HIP 60350. The ejection events had to be very violent, ejecting stars at velocities as large as 150 to 400 km/s.
