Interferometric radii of bright Kepler stars with the CHARA Array: θ Cygni and 16 Cygni A and B

Abstract

We present the results of long-baseline optical interferometry observations\nusing the Precision Astronomical Visual Observations (PAVO) beam combiner at\nthe Center for High Angular Resolution Astronomy (CHARA) Array to measure the\nangular sizes of three bright Kepler stars: {\\theta} Cygni, and both components\nof the binary system 16 Cygni. Supporting infrared observations were made with\nthe Michigan Infrared Combiner (MIRC) and Classic beam combiner, also at the\nCHARA Array. We find limb-darkened angular diameters of 0.753+/-0.009 mas for\n{\\theta} Cyg, 0.539+/-0.007 mas for 16 Cyg A and 0.490+/-0.006 mas for 16 Cyg\nB. The Kepler Mission has observed these stars with outstanding photometric\nprecision, revealing the presence of solar-like oscillations. Due to the\nbrightness of these stars the oscillations have exceptional signal-to-noise,\nallowing for detailed study through asteroseismology, and are well constrained\nby other observations. We have combined our interferometric diameters with\nHipparcos parallaxes, spectrophotometric bolometric fluxes and the\nasteroseismic large frequency separation to measure linear radii ({\\theta} Cyg:\n1.48+/-0.02 Rsun, 16 Cyg A: 1.22+/-0.02 Rsun, 16 Cyg B: 1.12+/-0.02 Rsun),\neffective temperatures ({\\theta} Cyg: 6749+/-44 K, 16 Cyg A: 5839+/-42 K, 16\nCyg B: 5809+/-39 K), and masses ({\\theta} Cyg: 1.37+/-0.04 Msun, 16 Cyg A:\n1.07+/-0.05 Msun, 16 Cyg B: 1.05+/-0.04 Msun) for each star with very little\nmodel dependence. The measurements presented here will provide strong\nconstraints for future stellar modelling efforts.\n