Variable stars in the Open Cluster M11 (NGC 6705)

TL;DR

This study conducted V-band photometric observations of the open cluster M11, discovering 82 variable stars and classifying their types, providing insights into stellar variability within this intermediate-age cluster.

Contribution

The paper presents the first comprehensive survey of variable stars in M11, identifying and classifying 82 variables, including many probable cluster members, based on detailed light curve analysis.

Findings

Discovered 82 variable stars in M11

Classified variables into five types including delta Scuti and eclipsing binaries

Many variables are probable cluster members

Abstract

V-band time-series CCD photometric observations of the intermediate-age open cluster M11 were performed to search for variable stars. Using these time-series data, we carefully examined light variations of all stars in the observing field. A total of 82 variable stars were discovered, of which 39 stars had been detected recently by Hargis et al. (2005). On the basis of observational properties such as variable period, light curve shape, and position on a color-magnitude diagram, we classified their variable types as 11 delta Scuti-type pulsating stars, 2 gamma Doradus-type pulsating stars, 40 W UMa-type contact eclipsing binaries, 13 Algol-type detached eclipsing binaries, and 16 eclipsing binaries with long period. Cluster membership for each variable star was deduced from the previous proper motion results (McNamara et al. 1977) and position on the color-magnitude diagram. Many pulsating stars and eclipsing binaries in the region of M11 are probable members of the cluster.