Gaia DR3 Analysis of Four Open Clusters Toward the Galactic Anticenter

TL;DR

This paper characterizes four open clusters in the Galactic anticenter using Gaia DR3 data, revealing their physical, kinematic, and dynamical properties, and confirming their role as tracers of thin-disc evolution.

Contribution

It provides a comprehensive analysis of four open clusters using Gaia DR3 data, including membership, structural, astrophysical, and dynamical properties, which was not previously detailed.

Findings

Clusters are moderately reddened, intermediate-age, 1-3.5 kpc from the Sun.

All clusters follow nearly circular, thin-disc-like orbits.

Clusters are dynamically evolved despite their young ages.

Abstract

This study provides a detailed examination of the structural, astrophysical, kinematic, and dynamical properties of the open clusters COIN-Gaia 24, Czernik 24, FSR 0893, and UBC 74, which are located in the direction opposite to the Galactic center. Astrometric, photometric, and spectroscopic data from the Gaia Data Release 3 catalog were used to ensure a precise characterization of cluster members and their physical properties. Membership determination was performed using the UPMASK algorithm applied to a five-dimensional parameter space, yielding 116, 179, 238, and 387 likely members for each cluster, respectively. Structural parameters were derived by fitting King profiles to the radial density distributions of high-probability members. Astrophysical parameters were estimated through Bayesian Markov Chain Monte Carlo isochrone fitting based on PARSEC evolutionary models, complemented by spectral energy distribution analysis using ARIADNE. The resulting extinctions, distances, metallicities, and ages indicate that these are moderately reddened, intermediate-age clusters located between 1 and 3.5 kpc from the Sun. Mean radial velocities combined with Galactic orbital integrations computed with galpy show that all four clusters follow nearly circular, low-eccentricity orbits typical of thin-disc populations. All four OCs have dynamical relaxation times of 22-98 Myr. However, their ages exceed these times by several factors, particularly in Czernik 24, indicating that they are dynamically evolved systems, even though the calculated T_E values represent lower limits. The results confirm that these OCs serve as reliable tracers of the chemical and dynamical evolution of the Galactic thin disc.