The OmegaWhite Survey for Short Period Variable Stars VI. Open Clusters

TL;DR

This study used high-cadence light curves from the OmegaWhite survey to identify and analyze short-period variable stars in 20 open clusters, finding mostly delta Scuti stars and confirming cluster membership for several.

Contribution

It presents the first systematic search for short-period variables in these clusters using OmegaWhite data, including membership determination and spectroscopic follow-up.

Findings

92 variable stars identified in open cluster fields

10 confirmed cluster members, 2 probable members

Most variables are delta Sct stars based on Gaia data

Abstract

Using light curves with $\sim$3 min cadence and a duration of 2 hrs made using the OmegaWhite survey, we present the results of a search for short-period variable stars in the field of 20 open clusters. We identified 92 variable stars in these fields. Using a range of cluster member catalogues and Gaia EDR3 data, we have determined that 10 are cluster members and 2 more are probable members. Based on their position on the Gaia HRD and their photometric periods, we find that most of these are $\delta$ Sct stars. We obtained low-resolution optical spectroscopy of some of these cluster members and field stars. We discuss the cluster variable stars in the context of $\delta$ Sct stars in other open clusters.