Interstellar extinction in the direction of the open cluster King 7 and new parameters of the cluster

Abstract

Interstellar extinction in two concentric square areas of the sizes 1.25 × 1.25 deg2and 0.2 × 0.2 deg2in the direction of open cluster King 7 is investigated applying two-dimensional photometric classification of stars observed in the Vilnius seven-color photometric system down to V = 15.5 mag (1084 stars) and 19.5 mag (584 stars), respectively. The cluster members (284 stars) are identified applying their coordinates, proper motions, and parallaxes taken from the Gaia EDR3 catalog. New parameters of the cluster (distance, diameter, interstellar extinction, and age) are obtained. Photogeometric distances of stars are taken from Bailer-Jones et al. (2021) based on the Gaia parallaxes from EDR3. Physically the cluster is located at the outer edge of the Perseus spiral arm at d = 2.74 kpc, its diameter is 9.6 pc, the age is 175 ± 25 Myr, the earliest stars are of spectral classes B6-B7. The average interstellar extinction AV= 4.24 mag. From the radial velocities of CO and the Galactic rotation curve we estimate distances to the nearby dust clouds TGU H989 P2 and P3 at 650-670 pc from the Sun. © 2021 Institute of Physics Publishing. All rights reserved.