Berkeley 76: An intermediate age open star cluster in Gaia Era

Abstract

We studied the open star cluster Berkeley 76 using Gaia DR3 and 2MASS data sets. We obtained 314 most probable cluster members with a membership probability greater than 80%. We have found the cluster center as $\alpha$ = 106.67 ± 0.07 deg and $\delta =-11.75\pm$0.07 deg. The mean PMs of cluster members in right ascension and declination are $-0.60\pm$0.22 and 1.35 ± 0.19 mas yr⁻¹, respectively. The radial density profile estimates the cluster’s radius to be 4.5 arcmin. The cluster’s heliocentric distance is estimated as 4.27${}^{\pm }$0.91 kpc, and its age is determined as $1.60\pm 0.35$ Gyr. Using the most probable cluster members, we determined the mass function slope for Berkeley 76 as $\mathrm{1.57\; \pm \; 0.19}$. This value is close to Salpeter’s slope within the uncertainty. Berkeley 76 is a dynamically relaxed cluster with a relaxation time of 23.4 Myr.