Variable Stars in the Open Cluster NGC 7142

TL;DR

This study reports new variable stars in NGC 7142, revises its distance and age estimates, and suggests it is a young cluster with stars at a key evolutionary transition.

Contribution

The paper discovers new variable stars in NGC 7142 and provides revised estimates of the cluster's distance, reddening, and age, offering new insights into its stellar population.

Findings

Eight contact or near contact eclipsing binaries detected

Distance to NGC 7142 is larger and reddening lower than previous estimates

Cluster age estimated at about 3 billion years

Abstract

We present new discoveries of variable stars near the turnoff of the old open cluster NGC 7142. Contrary to previous studies, we detect eight contact or near contact eclipsing binaries (including three near the cluster turnoff), and most of these have good probability of being cluster members. We also identified one long-period variable that resides far to the red of the cluster giant branch, and four new detached eclipsing binaries. We have re-examined the question of distance and reddening for the cluster, and find that the distance is larger and reddening lower than in most previous studies. In turn this implies that NGC 7142 is probably slightly younger than M67, about 3 Gyr old. With an age of this size, NGC 7142 would be one of a small group of clusters with main sequence turnoff stars at the transition between convective and radiative cores.