论文标题
萨吉塔斯矮人球体核心的金属分布：最小化金属性偏见
The metallicity distribution in the core of the Sagittarus dwarf spheroidal: minimising the metallicity biases
论文作者
论文摘要
我们提出了射手座矮人球形（SGR DSPH）星系的450个真正成员的金属性和径向速度，该星系是根据高分辨率（R〜18000）flames@vlt Spectra测得的。仔细选择靶标（a）来采样SGR DSPH主体的核心，同时避免了中央恒星核的污染，并且（b）通过根据其Gaia parallax和适当的运动来选择目标，以防止金属分布的任何偏差。以这种方式选择的所有目标都被确认为径向速度成员。我们使用该样品来得出SGR DSPH核心的第一个金属性分布，实际上不受金属性偏差的影响。观察到的分布范围从[fe/h]〜 -2.3到[fe/h] 〜0.0，在[fe/h]〜 -0.5周围具有强，对称和相对狭窄的峰，并且只有13.8 +/- 13.8 +/- 1.9％的恒星具有[Fe/H] <-1.0。我们证实了先前的SGR核心恒星化学和运动学性质之间相关性的证据。在我们的样品恒星中，与[Fe/H] <-0.6的样本> = -0.6显示出较低的速度分散剂和更高的旋转振幅，这证实了系统祖先的磁盘/光环结构的先前建议。
We present metallicity and radial velocity for 450 bonafide members of the Sagittarius dwarf spheroidal (Sgr dSph) galaxy, measured from high resolution (R~18000) FLAMES@VLT spectra. The targets were carefully selected (a) to sample the core of the main body of Sgr dSph while avoiding contamination from the central stellar nucleus, and (b) to prevent any bias on the metallicity distribution, by selecting targets based on their Gaia parallax and proper motions. All the targets selected in this way were confirmed as radial velocity members. We used this sample to derive the first metallicity distribution of the core of the Sgr dSph virtually unaffected by metallicity biases. The observed distribution ranges from [Fe/H]~ -2.3 to [Fe/H]~ 0.0, with a strong, symmetric and relatively narrow peak around [Fe/H]~ -0.5 and a weak, extended metal-poor tail, with only 13.8 +/- 1.9% of the stars having [Fe/H]< -1.0. We confirm previous evidence of correlations between chemical and kinematical properties of stars in the core of Sgr. In our sample stars with [Fe/H]>= -0.6 display a lower velocity dispersion and a higher rotation amplitude than those with [Fe/H]< -0.6, confirming previous suggestions of a disk/halo structure for the progenitor of the system.
