Identification of Outer Galaxy Cluster Members Using Gaia DR3 and Multidimensional Simulation

TL;DR

This paper introduces a new multidimensional clustering method using Gaia DR3 data and simulations to accurately identify members of outer Galaxy star clusters, including new member discoveries and improved distance estimates.

Contribution

The study develops a novel unsupervised clustering approach with Monte Carlo simulation and higher-dimensional analysis to improve cluster membership identification in distant, uncertain environments.

Findings

Discovery of new cluster members.

Validation of membership with known stars.

Distance estimates closely match Gaia and WISE data.

Abstract

The outer Galaxy presents a distinctive environment for investigating star formation. This study develops a novel approach to identify true cluster members based on unsupervised clustering using astrometry with significant uncertainties. As a proof of concept, we analyze three outer Galactic Young Stellar Object (YSO) clusters at different distances and densities within 65 < l < 265 degrees, each known to contain >100 members based on the Star Formation in Outer Galaxy catalog. The 618 YSO clusters in the SFOG dataset were based on 2-dimensional clustering. In this contribution, we apply the HDBSCAN* algorithm to the precise Gaia DR3 astrometry to assign YSO cluster membership. Monte Carlo simulation, coupled with HDBSCAN* (HDBSCAN-MC algorithm), addresses YSO astrometric uncertainties while 5-dimensional clustering. We introduce the Generation Of cLuster anD FIeld STar (GOLDFIST) simulation, to enable robust membership determination, performing an unsupervised clustering analysis in higher-dimensional feature space while accommodating measurement errors. In this study, we extended our approach to distant outer galaxy YSOs and clusters with larger astrometric uncertainties. The results include the discovery of new members in the previously identified clusters. We also analyze the known stars in the clusters and confirm their membership. The derived membership probabilities are included in the provided cluster catalogs. The more accurately predicted simulation distance estimates closely agree, within uncertainty limits, with the median distance estimates derived from Gaia data, and are compared with the kinematic distances from the WISE HII survey.