最远星表疏散星团的分析--用Gaia EDR3和$\texttt{ASteCA}$重新估算基本参数
An analysis of the most distant catalogued open clusters -- Re-assessing fundamental parameters with Gaia EDR3 and $\texttt{ASteCA}$
摘要：
在过去的几年里，已经提出了一些研究应用某种自动处理的数据来估计疏散星团的基本参数。这些参数后来被用于更大尺度的分析，例如银河系旋臂的结构。距离是最直接的参数之一，但在已发表的数据中仍然可以发现巨大的差异。这对于距离超过几千秒差距的疏散星团来说尤其如此。我们交叉比对了几个已发表的星表，并选择了25个最遥远的疏散星团（$>$ 9000 pc）。然后，我们对它们的基本参数进行了详细的分析，重点是它们的距离，以确定目录和我们的估计之间的一致性。使用了盖亚EDR 3巡天的光度和天体测量数据。数据处理与我们自己的隶属度分析代码（pyUPMASK），和我们的软件包自动基本聚类的参数估计（$\texttt{ASteCA}$）。我们发现我们的结果和那些编目之间的估计距离的差异高达几个千秒差距，即使是最好的匹配与$\texttt{ASteCA}$值的目录。年龄估计值也存在很大差异。作为分析的副产品，我们发现vd Bergh-Hagen 176可能是迄今为止编目的日心距离最大的疏散星团。因此，在使用疏散星团的星表参数来推断银河系的大尺度性质时，特别是对于那些位于几千秒差距以上的星系，我们强烈建议谨慎。
英文摘要：
Several studies have been presented in the last few years applying some kind of automatic processing of data to estimate the fundamental parameters of open clusters. These parameters are later on employed in larger scale analyses, for example the structure of the Galaxy's spiral arms. The distance is one of the more straightforward parameters to estimate, yet enormous differences can still be found among published data. This is particularly true for open clusters located more than a few kpc away. We cross-matched several published catalogues and selected the twenty-five most distant open clusters ($>$9000 pc). We then performed a detailed analysis of their fundamental parameters, with emphasis on their distances, to determine the agreement between catalogues and our estimates.} Photometric and astrometric data from the Gaia EDR3 survey was employed. The data was processed with our own membership analysis code (pyUPMASK), and our package for automatic fundamental cluster's parameters estimation ($\texttt{ASteCA}$). We find differences in the estimated distances of up to several kpc between our results and those catalogued, even for the catalogues that show the best matches with $\texttt{ASteCA}$ values. Large differences are also found for the age estimates. As a by-product of the analysis we find that vd Bergh-Hagen 176 could be the open cluster with the largest heliocentric distance catalogued to date. Caution is thus strongly recommended when using catalogued parameters of open clusters to infer large-scale properties of the Galaxy, particularly for those located more than a few kpc away.
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