标题： 使用聚类算法的疏散星团 NGC 1857 和 Czernik 20 的形态学研究 显示英文标题

标题： Morphology of Open Clusters NGC 1857 and Czernik 20 using Clustering Algorithms

摘要： 银河系疏散星团Czernik 20和NGC 1857的形态和成员星团使用两种不同的聚类算法进行了分析。我们首次使用基于密度的空间聚类应用与噪声（DBSCAN）来确定从空间分布中的疏散星团形态。分析区域也使用统计成员确定算法进行了空间分类。我们利用了来自英国红外深空天空调查银河平面调查恒星目录数据库和2微米全天调查恒星目录数据库的近红外（NIR）数据，用于这些星团周围足够大的区域。因此识别出的星团形态最密集区域（Czernik 20为1个，NGC 1857为2个）使用K波段消光图和颜色-星等图（CMDs）进行了分析。为了解决已知距离和消光参数之间的显著差异，我们对这些CMDs进行了场污染去除，并随后对清理后的CMDs进行等时线拟合，以获得这些星团的可靠距离和消光参数（Czernik 20：D = 2900 pc；E(J-K) = 0.33；NGC 1857：D = 2400 pc；E(J-K) = 0.18-0.19）。等时线还被用来将Czernik 20和NGC 1857最密集区域的光度函数转换为质量函数，以推导它们的斜率。此外，在分析区域中还发现了一个之前未知的高密度区，其特征与星团一致。 显示英文摘要

摘要： The morphology and cluster membership of the Galactic open clusters - Czernik 20 and NGC 1857 were analyzed using two different clustering algorithms. We present the maiden use of density-based spatial clustering of applications with noise (DBSCAN) to determine open cluster morphology from spatial distribution. The region of analysis has also been spatially classified using a statistical membership determination algorithm. We utilized near infrared (NIR) data for a suitably large region around the clusters from the United Kingdom Infrared Deep Sky Survey Galactic Plane Survey star catalogue database, and also from the Two Micron All Sky Survey star catalogue database. The densest regions of the cluster morphologies (1 for Czernik 20 and 2 for NGC 1857) thus identified were analyzed with a K-band extinction map and color-magnitude diagrams (CMDs). To address significant discrepancy in known distance and reddening parameters, we carried out field decontamination of these CMDs and subsequent isochrone fitting of the cleaned CMDs to obtain reliable distance and reddening parameters for the clusters (Czernik 20: D = 2900 pc; E(J-K) = 0.33; NGC 1857: D = 2400 pc; E(J-K) = 0.18-0.19). The isochrones were also used to convert the luminosity functions for the densest regions of Czernik 20 and NGC 1857 into mass function, to derive their slopes. Additionally, a previously unknown over-density consistent with that of a star cluster is identified in the region of analysis.