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arXiv · 2510.23375

Validating Open Cluster Candidates with Photometric Bayesian Evidence

Lu Li·Zhaozhou Li·Zhengyi Shao
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Abstract

The thousands of open cluster (OC) candidates identified by the Gaia mission are significantly contaminated by false positives from field star fluctuations, posing a major validation challenge. Based on the Mixture Model for OCs (MiMO), we present a Bayesian framework for validating OC candidates in the color--magnitude diagram. The method compares the Bayesian evidence of two competing models: a single stellar population with field contamination versus a pure field population. Their ratio, the Bayes factor (BF), quantifies the statistical support for cluster existence. Tests on confirmed clusters and random fields show that a threshold of BF > 100 effectively distinguishes genuine clusters from chance field overdensities. This approach provides a robust, quantitative tool for OC validation and catalog refinement. The framework is extendable to multi-dimensional validation incorporating kinematics and is broadly applicable to other resolved stellar systems, including candidate moving groups, stellar streams, and dwarf satellites.

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Lu Li, Zhaozhou Li, Zhengyi Shao. 2025-10-27. Validating Open Cluster Candidates with Photometric Bayesian Evidence. https://arxiv.org/abs/2510.23375

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