Discovery and astrophysical properties of Galactic open clusters in dense stellar fields using Gaia DR2

TL;DR

This study reports the discovery of 25 new open clusters in dense stellar fields using Gaia DR2 data, providing their structural and astrophysical parameters, and analyzing their properties within the Milky Way.

Contribution

The paper introduces a new method for identifying and characterizing open clusters in dense fields using Gaia DR2, including structural and astrophysical parameter estimation.

Findings

25 new open clusters discovered in dense fields

Clusters are mainly within 3 kpc from the Sun

Clusters have larger core radii and less concentration than previously known clusters

Abstract

We report the discovery of 25 new open clusters resulting from a search in dense low galactic latitude fields. We also provide, for the first time, structural and astrophysical parameters for the new findings and 34 other recently discovered open clusters using Gaia DR2 data. The candidates were confirmed by jointly inspecting the vector point diagrams and spatial distribution. The discoveries were validated by matching near known objects and comparing their mean astrometric parameters with the available literature. A decontamination algorithm was applied to the three-dimensional astrometric space to derive membership likelihoods for clusters stars. By rejecting stars with low membership likelihoods, we built decontaminated colour-magnitude diagrams and derived the clusters astrophysical parameters by isochrone fitting. The structural parameters were also derived by King-profile fittings over the stellar distributions. The investigated clusters are mainly located within 3 kpc from the Sun, with ages ranging from 30 Myr to 3.2 Gyr and reddening limited to E(B-V)=2.5. On average, our cluster sample presents less concentrated structures than Gaia DR2 confirmed clusters, since the derived core radii are larger while the tidal radii are not significantly different. Most of them are located in the IV quadrant of the Galactic disc at low latitudes, therefore they are immersed in dense fields characteristic of the inner Milky Way.