Searching for short-period variable stars in the direction of Coma Berenices and Upgren 1 open clusters: Melotte 111 AV 1224 a new eclipsing binary star

TL;DR

This study used CCD photometry to search for short-period variable stars in two open clusters, discovering a new eclipsing binary star, Melotte 111 AV 1224, and analyzing its properties.

Contribution

First detection and characterization of a new eclipsing binary star in the direction of open clusters, with detailed photometric and spectroscopic analysis.

Findings

Melotte 111 AV 1224 is a likely W UMa eclipsing binary.

No brightness variations found in previously catalogued variables NSV 5612 and NSV 5615.

Melotte 111 AV 1224 is probably not a cluster member.

Abstract

We report the results of CCD photometric observations in the direction of the Coma Berenices and Upgren 1 open clusters with the aim at searching for new short-period variable stars. A total of 35 stars were checked for variability. As a result of this search the star designated in the SIMBAD database as Melotte 111 AV 1224 was found to be a new eclipsing binary star. Follow-up Str\"omgren photometric and spectroscopic observations allowed us to derive the spectral type, distance, reddening and effective temperature of the star. A preliminary analysis of the binary light curve was performed and the parameters of the orbital system were derived. From the derived physical parameters we conclude that Melotte 111 AV 1224 is most likely a W UMa eclipsing binary that is not a member of the Coma Berenices open cluster. On other hand, we did not find evidence of brightness variations in the stars NSV 5612 and NSV 5615 previously catalogued as variable stars in Coma Berenices open cluster.