Gaia astrometric and photometric study of open clusters (Dolidze 18 & Ruprecht 70)

TL;DR

This study uses Gaia DR2 data to analyze two previously unstudied open clusters, determining their physical parameters, sizes, and dynamical states with improved accuracy.

Contribution

First photometric and astrometric analysis of Dolidze-18 and Ruprecht-70 using Gaia DR2, providing new insights into their structure, parameters, and dynamical status.

Findings

Ruprecht-70 is dynamically relaxed.

Dolidze-18 is not yet dynamically relaxed.

Cluster sizes are larger when measured with Gaia data.

Abstract

Here, we conducted a photometric and astrometric study of two open stellar clusters Dolidze-18 and Ruprecht-70, which have not been photometrically studied before. The most important thing for using Gaia (DR2) database lies in the positions, parallax, and proper motions, which make us split cluster members from the field ones and get precise astrophysical parameters. On studying the radial density profiles of these clusters, the actual sizes are estimated and found larger using Gaia. From the color-magnitude diagrams and theoretical isochrones, we simultaneously determined the ages, distance moduli, and reddening of the two clusters. However, considering the parallaxes of Gaia (DR2) for the cluster members, we calculated the cluster distance and confirmed what we obtained from the color-magnitude diagram. Then, the Cartesian galactocentric coordinates (Xo, Yo, Zo), and the distances from the galactic center (Rg) were also estimated. According to the luminosity and mass functions, the total luminosity and total mass of the clusters are estimated. Our study shows that Ruprecht-70 is recently dynamically relaxed, while Dolidze 18 is not relaxed yet.