Fundamental parameters for 45 open clusters with Gaia DR2, an improved extinction correction and a metallicity gradient prior

TL;DR

This study uses Gaia DR2 data to accurately determine fundamental parameters of 45 open clusters, improving extinction correction and incorporating a metallicity gradient prior, thereby enhancing our understanding of Galactic structure.

Contribution

Introduces an improved method for estimating open cluster parameters using Gaia DR2, including refined extinction correction and metallicity prior, with new radial velocity measurements for several clusters.

Findings

Accurate proper motions and parallaxes for 45 clusters

Radial velocities obtained for 12 clusters, 7 newly measured

Enhanced isochrone fitting with updated extinction and metallicity models

Abstract

Reliable fundamental parameters of open clusters such as distance, age and extinction are key to our understanding of Galactic structure and stellar evolution. In this work we use {\it Gaia} DR2 to investigate 45 open clusters listed in the \emph{New catalogue of optically visible open clusters and candidates} (DAML) but with no previous astrometric membership estimation based on {\it Gaia} DR2. In the process of selecting targets for this study we found that some clusters reported as new discoveries in recent papers based on {\it Gaia} DR2 were already known clusters listed in DAML. Cluster memberships were determined using a maximum likelihood method applied to {\it Gaia} DR2 astrometry. This has allowed us to estimate mean proper motions and mean parallaxes for all investigated clusters. Mean radial velocities were also determined for 12 clusters, 7 of which had no previous published values. We have improved our isochrone fitting code to account for interstellar extinction using an updated extinction polynomial for the {\it Gaia} DR2 photometric band-passes and the Galactic abundance gradient as a prior for metallicity. The updated procedure was validated with a sample of clusters with high quality $[Fe/H]$ determinations. We then did a critical review of the literature and verified that our cluster parameter determinations represent a substantial improvement over previous values.