A detection of the layered structure of nearby open clusters

TL;DR

This study introduces a new rose diagram overlay method to detect and analyze the layered structures of nearby open clusters, revealing correlations with cluster member counts and providing new structural parameters.

Contribution

The paper presents a novel rose diagram overlay technique for identifying layered structures in open clusters and defines new parameters for their characterization.

Findings

74 out of 88 clusters exhibit layered structures

Layered circle core area correlates positively with cluster size

Kernel instability index correlates negatively with cluster size

Abstract

We applied the newly developed rose diagram overlay method to detect the layered structure of 88 nearby open clusters ($\leq$500~pc) on the three projections after the distance correction of their member stars, based on the catalog in literature. The results show that with the rose diagram overlay method, a total of 74 clusters in our sample have a layered structure, while the remaining clusters are without a clear layered structure. We for the first time defined the layered structure parameters for the sample clusters. Meanwhile, we found that the layered circle core area ($s$) has a strong positive correlation with the number of cluster members, while the kernel instability index ($\eta$) has a strong negative correlation with the number of cluster members. Our study provides a novel perspective for the detection of the layered structure of open clusters.