Astrometric star-cluster membership probability: application to the case of M 37 with Gaia EDR3

TL;DR

This paper introduces a new formalism for calculating star cluster membership probabilities using Gaia EDR3 data, with a focus on M 37, by refining the parallax distribution modeling to improve accuracy.

Contribution

It presents a novel, magnitude-dependent model for field star parallax distribution and applies it to determine cluster membership in M 37.

Findings

Refined parallax distribution model improves membership probability accuracy

Derived precise astrometric parameters for M 37

Enhanced understanding of cluster membership with Gaia EDR3 data

Abstract

In this work, starting from the well-accepted relations in literature, we introduce a new formalism to compute the astrometric membership probabilities for sources in star clusters, and we provide an application to the case of the open cluster M 37. The novelty of our approach is a refined -- and magnitude-dependent -- modelling of the parallax distribution of the field stars. We employ the here-derived list of members to estimate the cluster's mean systemic astrometric parameters, which are based on the most recent Gaia's catalog (EDR3).