墙上的三块新砖：Berkeley 23，Berkeley 31和King 8
Three new bricks in the wall: Berkeley 23, Berkeley 31, and King 8
摘要：
对银河系疏散星团性质的全面普查对银河系盘的结构和演化提出了独特的限制。在这个框架中，我们调查了三个缺乏研究的疏散星团，伯克利31，伯克利23和国王8，都位于银河系的反中心方向的演化状态。为了这个目的，我们利用深LBT观测，达到超过6个MAG以下的主序列关闭。为了确定集群参数，即年龄，金属丰度，距离，红化和二进制分数，我们比较观测的颜色-星等图（CMD）与不同的进化集（帕多瓦，法国和FST）和金属丰度产生的合成CMD库。我们发现伯克利31相对较老，年龄在2.3到2.9 Gyr之间，并且在银河平面上方相当高，大约700 pc。伯克利23岁和国王8岁更年轻，最适合的年龄范围分别为1.1-1.3 Gyr和0.8-1.3 Gyr。在银河平面上方的位置，前者约为500- 600 pc，后者约为200 pc。虽然需要光谱确认，但我们的分析表明，这三个星团的金属丰度都低于太阳。
英文摘要：
A comprehensive census of Galactic open cluster properties places unique constraints on the Galactic disc structure and evolution. In this framework we investigate the evolutionary status of three poorly-studied open clusters, Berkeley 31, Berkeley 23 and King 8, all located in the Galactic anti-centre direction. To this aim, we make use of deep LBT observations, reaching more than 6 mag below the main sequence Turn- Off. To determine the cluster parameters, namely age, metallicity, distance, reddening and binary fraction, we compare the observational colour-magnitude diagrams (CMDs) with a library of synthetic CMDs generated with different evolutionary sets (Padova, FRANEC and FST) and metallicities. We find that Berkeley 31 is relatively old, with an age between 2.3 and 2.9 Gyr, and rather high above the Galactic plane, at about 700 pc. Berkeley 23 and King 8 are younger, with best fitting ages in the range 1.1-1.3 Gyr and 0.8-1.3 Gyr, respectively. The position above the Galactic plane is about 500- 600 pc for the former, and 200 pc for the latter. Although a spectroscopic confirmation is needed, our analysis suggests a sub-solar metallicity for all three clusters.
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。
