The statistical analysis of the Galactic open clusters’ structure

ABSTRACT We present a systematic investigation of 1481 Galactic open clusters (OCs) through the application of the limepy dynamical model, from which we derive the fundamental structural parameters of OCs. We conduct the statistical analyses on the structural parameters with clusters’ ages and locations within the Milky Way. Our results reveal that the higher concentration in the cluster centre is associated with the sharper truncation at the periphery of cluster, which is consistent with previous findings for globular clusters. We further find the systematic increase of the lower limit of clusters’ half-mass radius ($R_\mathrm{ h}$) with age. Our results also show that OCs located at larger vertical distances from the Galactic plane systematically display higher central concentrations. Our findings collectively suggest that the structural characteristics of OCs are shaped by both intrinsic evolutionary processes and interactions with the Galactic environment. During the evolution of star clusters, the combined effects of mass segregation and tidal stripping lead to the systematic pattern between central concentration and outer truncation. Clusters of different ages and locations within the Milky Way undergo different evolutionary histories, resulting in correlations between the $R_{\rm h}$ and age, as well as between central concentration and Galactic location.