论文标题
小麦哲伦云中剥离的明星簇的第一个证据
First evidence of a stripped star cluster from the Small Magellanic Cloud
论文作者
论文摘要
我们介绍了最近发现的恒星系统YMCA-1的结果，该系统的物理性质和属于任何麦哲伦系统星系的物理性质和属于任何一个。我们使用了Smash和{\ it Gaia} EDR3数据集来得出结论，我们正在处理一个小星团。探索了其发红的田间恒星净化颜色 - 磁性图，以获取群集参数。我们发现YMCA-1是一个小的（435 m $ _ {\ odot} $），中度年龄（年龄= 9.6 Gyr），中等金属罚款（[Fe/h] = -1.16 dex）星团，位于几乎很小的麦克云（SMC）距离（60.9 kpc）$ 17的$ 17.云（LMC）中心。衍生的聚集亮度和尺寸似乎暗示着与最近在银河系（MW）外光环的最近发现的微弱的明星簇相似，尽管它与它们的年龄 - 金属关系的关系不符，也不符合MW球形群集的相似之处，或者与LMC Clusters In-Situ或Ex-Situ形成的Globular clusters call clusters call calc cals caster calc smc smc star clusters calc celters calc calc calc calc calc calc calc cal call call call call call call call call calt call calt call calt call calt calls上均高。我们进行了数值蒙特卡洛模拟，将其轨道运动在MW-LMC-SMC系统中向后整合，并具有径向扩展的暗物质光环，并通过探索YMCA-1的不同径向速度（RV）方案。对于RVS $ \ gtrsim $ 300 km/s，该集群在最后500 MYRS中仍与LMC绑定。 YMCA-1的详细跟踪运动学表明，在两个星系之间的任何紧密相互作用期间，SMC都可以从SMC中剥离它，这是数值模拟以前预测的情况。
We present results on the recently discovered stellar system YMCA-1, for which physical nature and belonging to any of the Magellanic System galaxies have been irresolutely analyzed. We used SMASH and {\it Gaia} EDR3 data sets to conclude that we are dealing with a small star cluster. Its reddening free, field star decontaminated colour-magnitude diagram was explored in order to obtain the cluster parameters. We found that YMCA-1 is a small (435 M$_{\odot}$), moderately old (age = 9.6 Gyr), moderately metal-poor ([Fe/H] = -1.16 dex) star cluster, located at a nearly Small Magellanic Cloud (SMC) distance (60.9 kpc) from the Sun, at $\sim$ 17.1 kpc to the East from the Large Magellanic Cloud (LMC) centre. The derived cluster brightness and size would seem to suggest some resemblance to the recently discovered faint star clusters in the Milky Way (MW) outer halo, although it does not match their age-metallicty relationship, nor those of MW globular clusters formed in-situ or ex-situ, nor that of LMC clusters either, but is in agreement with that of SMC old star clusters. We performed numerical Monte Carlo simulations integrating its orbital motion backward in the MW-LMC-SMC system with radially extended dark matter haloes that experience dynamical friction, and by exploring different radial velocity (RV) regimes for YMCA-1. For RVs $\gtrsim$ 300 km/s, the cluster remains bound to the LMC during the last 500 Myrs. The detailed tracked kinematic of YMCA-1 suggests that its could have been stripped by the LMC from the SMC during any of the close interactions between both galaxies, a scenario previously predicted by numerical simulations.
