Tidal tails in the disintegrating open cluster NGC 752

Abstract

We utilize the robust membership determination algorithm, ML-MOC, on the precise astrometric and deep photometric data from Gaia Early Data Release 3 within a region of radius 5${}^{\circ }$ around the center of the intermediate-age galactic open cluster NGC 752 to identify its member stars. We report the discovery of the tidal tails of NGC 752, extending out to $\sim$35 pc on either side of its denser central region and following the cluster orbit. From comparison with PARSEC stellar isochrones, we obtain the mass function of the cluster with a slope, $\chi =-1.26\pm 0.07$. The high negative value of $\chi$ is indicative of a disintegrating cluster undergoing mass-segregation. $\chi$ is more negative in the intra-tidal regions as compared to the outskirts of NGC 752. We estimate a present day mass of the cluster, M${}_{\mathrm{C}}=297\pm 10$ M${}_{\odot }$. Through mass-loss due to stellar evolution and tidal interactions, we further estimate that NGC 752 has lost nearly 95.2-98.5 % of its initial mass, ${\mathrm{M}}_{\mathrm{i}}=0.64-2\times 10^4{\mathrm{M}}_{\odot }$.

7 pages, 6 figures; Accepted for publication in MNRAS