Kepler Binary Stars in the NGC 6819 Open Cluster: KIC 5113146 and KIC 5111815

Abstract

In this study, an investigation of two double-lined binary stars KIC 5113146 and KIC 5111815 in the NGC 6819 open cluster is presented based on both photometric and spectroscopic data. Simultaneous analysis of light and radial velocity curves was made and the absolute parameters of the systems' components were determined for the first time. We find that both systems have F-type main-sequence components. The masses and radii were found to be M-1 = 1.29 +/- 0.02M(circle dot), R-1 = 1.47 +/- 0.03 R-circle dot and M-2 = 1.19 +/- 0.02 M-circle dot, R-2 = 1.13 +/- 0.02 R-circle dot for the primary and secondary components of KIC 5113146; and M-1 = 1.51 +/- 0.08 M-circle dot, R-1 = 2.02 +/- 0.05 R-circle dot and M-2 = 1.19 +/- 0.07 M-circle dot, R-2 = 1.32 +/- 0.04 R-circle dot for the components of KIC 5111815, respectively. The evolutionary status of the components was evaluated based on the MESA evolutionary tracks and isochrones. The ages of KIC 5111815 and KIC 5113146 were derived to be about 2.50 +/- 0.35 Gyr and 1.95 +/- 0.40 Gyr, respectively. Photometric distances were calculated to be 2850 +/- 185 pc for KIC 5113146 and 3120 +/- 260 pc for KIC 5111815. The results reveal that both KIC 5113146 and KIC 5111815 systems are the most likely members of NGC 6819.