论文标题
原始的矮人 - 盖拉克斯调查-III。揭示银河系的本质球状射手座二世
The Pristine Dwarf-Galaxy survey -- III. Revealing the nature of the Milky Way globular cluster Sagittarius II
论文作者
论文摘要
我们提出了一项关于淡淡的银河系卫星射手座II的新光谱研究。使用来自纤维大阵列多元元素光谱仪的多对象光谱，我们补充了Longeard等人的数据集。 （2020）有47个新观察到的恒星，其中19个被确定为卫星的成员。这些额外的成员恒星用于对系统的动力学和金属性特性提出更严格的约束。我们发现SGRII v = 1.7 +/- 0.5 km S-1的低速分散体与银河系相似亮度的球状簇的分散体一致。我们确认了卫星的非常贫穷的性质（[[Fe/H] _sgrii = -2.23 +/- 0.07），并发现SGR II的金属性分散剂无法解决，在95％的置信度上只能达到0.20。毫无疑问地检测到低于-2.5的金属性的恒星。因此，尽管系统的大小异常大（RH = 35.5 +1.4-1.2 PC），但我们得出结论，SGR II是银河系中的旧且贫穷的球状簇。
We present a new spectroscopic study of the faint Milky Way satellite Sagittarius II. Using multi-object spectroscopy from the Fibre Large Array Multi Element Spectrograph, we supplement the dataset of Longeard et al. (2020) with 47 newly observed stars, 19 of which are identified as members of the satellite. These additional member stars are used to put tighter constraints on the dynamics and the metallicity properties of the system. We find a low velocity dispersion of SgrII v = 1.7 +/- 0.5 km s-1, in agreement with the dispersion of Milky Way globular clusters of similar luminosity. We confirm the very metal-poor nature of the satellite ([Fe/H]_SgrII = -2.23 +/- 0.07) and find that the metallicity dispersion of Sgr II is not resolved, reaching only 0.20 at the 95% confidence limit. No star with a metallicity below -2.5 is confidently detected. Therefore, despite the unusually large size of the system (rh = 35.5 +1.4-1.2 pc), we conclude that Sgr II is an old and metal-poor globular cluster of the Milky Way.
