论文标题
Viscacha调查-V。恢复了三个微弱的SMC簇
The VISCACHA survey -- V. Rejuvenating three faint SMC clusters
论文作者
论文摘要
我们介绍了小麦芽岩RZ82，HW42和RZ158的三个微弱簇的分析。我们用自适应光学元件使用了Soar望远镜仪器SAM，使我们能够前所未有地到达v〜23-24 mag，这一深度足以测量最高约10-12GYR的年龄。所有三个集群都分配到其中心，所得的颜色含量图（CMDS）使我们能够分别得出3.9、2.6和4.8GYR的年龄。这些结果明显比以前的确定（分别为7.1、5.0和8.3GYR）基于集成的光度法或较浅的CMD。我们根据深度光度法和统计等同型拟合来排除这些簇的年龄较大的年龄。我们还分别估算了[Fe/H] = -0.68，-0.57和-0.90的三个簇的金属度。这些更新的年龄和金属性与大部分SMC群集的年龄金属关系非常吻合。从综合通量估算了〜7-11x10^3MO的总簇质量，与其他类似年龄的SMC簇估计的质量一致。这些结果减少了已知年龄大于5 GYR的SMC簇的数量，并突出了需要深层和空间分辨的光度法以确定较旧的低亮度SMC星团簇的准确年龄。
We present the analysis of three faint clusters of the Small Magellanic Cloud RZ82, HW42 and RZ158. We employed the SOAR telescope instrument SAM with adaptive optics, allowing us to reach to V~23-24 mag, unprecedentedly, a depth sufficient to measure ages of up to about 10-12Gyr. All three clusters are resolved to their centres, and the resulting colour-magnitude diagrams (CMDs) allow us to derive ages of 3.9, 2.6, and 4.8Gyr respectively. These results are significantly younger than previous determinations (7.1, 5.0, and 8.3Gyr, respectively), based on integrated photometry or shallower CMDs. We rule out older ages for these clusters based on deep photometry and statistical isochrone fitting. We also estimate metallicities for the three clusters of [Fe/H]=-0.68, -0.57 and -0.90, respectively. These updated ages and metallicities are in good agreement with the age-metallicity relation for the bulk of SMC clusters. Total cluster masses ranging from ~7-11x10^3Mo were estimated from integrated flux, consistent with masses estimated for other SMC clusters of similar ages. These results reduce the number of SMC clusters known to be older than about 5 Gyr and highlight the need of deep and spatially resolved photometry to determine accurate ages for older, low-luminosity SMC star clusters.
