Ruprecht 147：作为恒星天体物理学新基准的最古老的附近疏散星团
Ruprecht 147: The oldest nearby open cluster as a new benchmark for stellar astrophysics
摘要：
Ruprecht 147是一个迄今为止不受重视的疏散星团，它在基础恒星天体物理学中具有很大的希望。我们已经进行了径向速度调查的天体测量的候选人与利克，帕洛玛和MMT天文台，并确定了100多名成员，包括5个蓝离散，11个红巨星，和5个双线光谱双星（SB 2）。我们使用光谱学简易（SME）从光谱分析估计簇金属度，并且发现它是[M/H] = +0.07 \pm 0.03。我们已经获得了深度CFHT/MegaCam g 'r'i'测光，并使用Naylor（2009）的τ^2最大似然程序和本工作中开发的使用二维互相关的替代方法将帕多瓦等时线拟合到（g' -i '）和2 MASS（J-K）CMD。我们发现年龄t = 2.5 \pm 0.25 Gyr，m - M = 7.35 \pm 0.1，和A_V = 0.25 \pm 0.05时等时线的最佳拟合，与未解决的二进制人口和差异灭绝的可能性在这个大集群的额外的不确定性。推断的年龄很大程度上取决于我们选择的恒星演化模型：拟合达特茅斯和PARSEC模型分别产生3 Gyr和3.25 Gyr的年龄参数。Ruprecht 147大约有300 pc和3 Gyr，是迄今为止附近最古老的星团。
英文摘要：
Ruprecht 147 is a hitherto unappreciated open cluster that holds great promise as a standard in fundamental stellar astrophysics. We have conducted a radial velocity survey of astrometric candidates with Lick, Palomar, and MMT observatories and have identified over 100 members, including 5 blue stragglers, 11 red giants, and 5 double-lined spectroscopic binaries (SB2s). We estimate the cluster metallicity from spectroscopic analysis, using Spectroscopy Made Easy (SME), and find it to be [M/H] = +0.07 \pm 0.03. We have obtained deep CFHT/MegaCam g'r'i' photometry and fit Padova isochrones to the (g' - i') and 2MASS (J - K) CMDs using the τ^2 maximum-likelihood procedure of Naylor (2009), and an alternative method using 2D cross-correlations developed in this work. We find best fits for isochrones at age t = 2.5 \pm 0.25 Gyr, m - M = 7.35 \pm 0.1, and A_V = 0.25 \pm 0.05, with additional uncertainty from the unresolved binary population and possibility of differential extinction across this large cluster. The inferred age is heavily dependent by our choice of stellar evolution model: fitting Dartmouth and PARSEC models yield age parameters of 3 Gyr and 3.25 Gyr respectively. At approximately 300 pc and 3 Gyr, Ruprecht 147 is by far the oldest nearby star cluster.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
