Photometric and kinematical analysis of Koposov 12 and Koposov 43 open clusters

Abstract

We present a photometric and kinematical analysis of two poorly studied open clusters, Koposov 12 (FSR 802) and Koposov 43 (FSR 848), by using cross-matched data from PPMXL and Gaia DR2 catalogs. We used astrometric parameters to identify 285 and 310 cluster members for Koposov 12 and Koposov 43, respectively. Using the extracted member candidates and isochrone fitting to near-infrared (J, H, and K_s) and Gaia DR2 bands (G, G_BP, and G_RP), and color-magnitude diagrams (CMDs), we have estimated ages: log(age yr⁻¹) = 9.00 $\pm$ 0.20 and 9.50 $\pm$ 0.20 and distances d = 1850 $\pm$ 43 and 2500 $\pm$ 50 pc for Koposov 12 and Koposov 43, respectively, assuming solar metallicity ($Z=0.019$). The estimated masses of the cluster derived using the initial mass function and synthetic (CMD) are $364\pm 19$ and $352\pm 19\,M_{\odot }$, respectively. We have also computed their velocity ellipsoid parameters based on ($3\times 3$) matrix elements ($\mu _{{ij}}$).