Bright Variable Stars in NGC 6819 - An Open Cluster in the Kepler Field

Abstract

We describe a variability study of the moderately old open cluster NGC 6819. We have detected 4 new detached eclipsing binaries near the cluster turnoff (one of which may be in a triple system). Several of these systems should be able to provide mass and radius information, and can therefore constrain the age of the cluster. We have also newly detected one possible detached binary member about 3.5 magnitudes below the turnoff. One EW-type binary (probably not a cluster member) shows unusually strong night-to-night light curve variations in sets of observations separated by 8 years. According to the best current information, the three brightest variables we detected (2 of them new) are cluster members, making them blue stragglers. One is a delta Scu pulsating variable, one is a close but detached binary, and the third contains a detached short period binary that shows total eclipses. In each case, however, there is evidence hinting that the system may have been produced through the interaction of more than two stars.

33 pages, 15 figures, accepted to AJ

References in corpus (2)

• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• WIYN Open Cluster Study. XXXVI. Spectroscopic Binary Orbits in NGC 188

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• The Dynamical Significance of Triple Star Systems in Star Clusters
• WOCS 40007: A Detached Eclipsing Binary near the Turnoff of the Open Cluster NGC 6819
• A Long-Period Totally Eclipsing Binary Star at the Turnoff of the Open Cluster NGC 6819 Discovered with Kepler
• Determining the Age of the Kepler Open Cluster NGC 6819 With a New Triple System and Other Eclipsing Binary Stars
• WIYN Open Cluster Study : Wide-Field CCD Photometry of the Old Open Cluster NGC 6819
• Asteroseismic Study on Cluster Distance Moduli for RGB Stars in NGC 6791 and NGC 6819
• CCD UBV photometry of the open cluster NGC 6819
• Variable Stars in the Open Cluster NGC 7142
• The Kepler IRIS Catalog: Image subtraction light curves for 9,150 stars in and around the open clusters NGC 6791 and NGC 6819
• Constraining the properties of delta Scuti stars using spectroscopic eclipsing binary systems
• Variable Blue Straggler Stars in Open Cluster NGC 6819 Observed in the Kepler 'Superstamp' Field