CCD UBV photometry of the open cluster NGC 6819

TL;DR

This study provides detailed CCD UBV photometry and analysis of the open cluster NGC 6819, deriving its physical, chemical, and orbital parameters to enhance understanding of its structure and evolution.

Contribution

First comprehensive CCD UBV photometric analysis of NGC 6819 including structural, astrophysical, and orbital parameters with new estimates of reddening, metallicity, distance, and age.

Findings

Reddening E(B-V)=0.130 mag and metallicity [Fe/H]=+0.051 dex.

Distance of 2309 pc and age of 2.4 Gyr.

Cluster has a slightly eccentric galactic orbit with e=0.06.

Abstract

We present the results of CCD UBV observations of the open cluster NGC 6819. We calculated the stellar density profile in the cluster's field to determine the structural parameters of NGC 6819. Using the existing astrometric data, we calculated the probabilities of the stars being physical members of the cluster, and used these objects in the determination of the astrophysical parameters of NGC 6819. We inferred the reddening and metallicity of the cluster as $E(B-V)=0.130\pm0.035$ mag and $[Fe/H]=+0.051\pm 0.020$ dex, respectively, using the U-B vs B-V two-colour diagram and UV excesses of the F-G type main-sequence stars. We fit the colour-magnitude diagrams of NGC6819 with the PARSEC isochrones and derived the distance modula, distance and age of the cluster as $\mu_{V}=12.22\pm 0.10$ mag, $d=2309\pm106$ pc and $t=2.4\pm0.2$ Gyr, respectively. The parameters of the galactic orbit estimated for NGC 6819 indicate that the cluster is orbiting in a slightly eccentric orbit of $e=0.06$ with a period of $P_{orb}=142$ Myr. The slope of the mass function estimated for the cluster is close to the one found for the stars in the solar neighbourhood.