Photometric and kinematic studies of open cluster NGC 1027

Abstract

We present photometric and kinematic analyses of an intermediate-age open cluster NGC 1027 using ${UBV(RI)}_c$ and Gaia Early Data Release 3 (EDR3) data. Structural and fundamental parameters, such as cluster center, cluster extent, reddening, age and distance are estimated in this study. Cluster center is found about 4 arcmin away from the center reported earlier. Radius has been estimated to be about 8.00 arcmin (2.65 pc). Using proper motion Gaia EDR3 data, membership probabilities have been derived for the stars in the region of cluster radius. We found mean proper motion of the cluster to be $\sim$(−0.84, 2.04) mas yr$^{-1}$ in (RA, DEC). We found 217 most probable ($P_\mu>$ 70%) cluster members with mean parallax $0.892 \pm 0.088$ mas. Out of these, 160 members have counterparts in our optical observations. Few stars having $P_\mu > 70$%, are found out of the cluster radius showing imprints of dynamical evolution. The color–color and color–magnitude diagrams for the cluster members found within 8.00 arcmin have been constructed using ${UBV(RI)}_c$ photometry and Gaia EDR3 data. This yields a reddening $E(B-V) \sim 0.36$ mag, age $\sim$130 Myr and distance $\sim$1.14 kpc. The mass function slope in the cluster region is $\Gamma \sim -1.46 \pm 0.15$, which is similar to other Galactic open clusters. The dynamical study shows lack of faint stars in its inner region leading to mass segregation effect. A comparison of dynamical age with cluster age indicates that NGC 1027 is a dynamically relaxed cluster suggesting that mass segregation may be imprint of its dynamical relaxation.