We present the results of long-baseline optical interferometry observations using the Precision Astronomical Visual Observations ( PAVO ) beam combiner at the Center for High Angular Resolution Astronomy ( CHARA ) Array to measure the angular sizes of three bright Kepler stars : \theta Cygni , and both components of the binary system 16 Cygni .
Supporting infrared observations were made with the Michigan Infrared Combiner ( MIRC ) and Classic beam combiner , also at the CHARA Array .
We find limb-darkened angular diameters of 0.753 \pm 0.009 mas for \theta Cyg , 0.539 \pm 0.007 mas for 16 Cyg A and 0.490 \pm 0.006 mas for 16 Cyg B .
The Kepler Mission has observed these stars with outstanding photometric precision , revealing the presence of solar-like oscillations .
Due to the brightness of these stars the oscillations have exceptional signal-to-noise , allowing for detailed study through asteroseismology , and are well constrained by other observations .
We have combined our interferometric diameters with Hipparcos parallaxes , spectrophotometric bolometric fluxes and the asteroseismic large frequency separation to measure linear radii ( \theta Cyg : 1.48 \pm 0.02 R _ { \odot } , 16 Cyg A : 1.22 \pm 0.02 R _ { \odot } , 16 Cyg B : 1.12 \pm 0.02 R _ { \odot } ) , effective temperatures ( \theta Cyg : 6749 \pm 44 K , 16 Cyg A : 5839 \pm 42 K , 16 Cyg B : 5809 \pm 39 K ) , and masses ( \theta Cyg : 1.37 \pm 0.04 M _ { \odot } , 16 Cyg A : 1.07 \pm 0.05 M _ { \odot } , 16 Cyg B : 1.05 \pm 0.04 M _ { \odot } ) for each star with very little model dependence .
The measurements presented here will provide strong constraints for future stellar modelling efforts .