A deep investigation of two poorly studied open clusters Haffner 22 and Melotte 71 in Gaia era

TL;DR

This study uses Gaia EDR3 data to analyze two open clusters, determining their membership, ages, distances, binary fractions, and orbital paths, revealing mass segregation and binary content variations.

Contribution

It provides a comprehensive analysis of Haffner 22 and Melotte 71 using Gaia data, including membership, ages, binary fractions, and orbital dynamics, which were previously poorly studied.

Findings

Membership probabilities for cluster members identified.

Ages of 2.25 Gyr and 1.27 Gyr determined.

Clusters follow circular Galactic orbits.

Abstract

This paper presents a deep investigation of two open clusters, Haffner 22 and Melotte 71, using astrometric and photometric data from Gaia EDR3. We identified 382 and 597 most probable cluster members with membership probability higher than 50 percent. Mean proper motion in RA and DEC are estimated as -1.63 and 2.889 respectively for Haffner 22 and -2.398 and 4.210 for Melotte 71. A comparison of observed CMDs with theoretical isochrones leads to an age of 2.25 and 1.27 Gyr for these clusters. The distances 2.88 and 2.28 kpc based on parallax are comparable with the values derived by isochrone fitting method. Five and four blue straggler stars are identified as cluster members in Haffner 22 and Melotte 71 respectively. Based on the relative number of high velocity (binary) and single stars, we inferred binary fractions for both clusters. We found binary content is larger in core region. Mass function slope is in good agreement with the Salpeter's value while it is flat for Haffner 22. Evidence for the existence of mass segregation effect is observed in both clusters. Using the Galactic potential models, Galactic orbits are derived, indicating that both clusters follow a circular path around the Galactic center, evolving slowly.