Huber, DIreland, MichaelBedding, Timothy RussellHowell, Steve BMaestro, VMerand, ATuthill, Peter GWhite, T. RFarrington, CGoldfinger, P. JMcAlister, HSchaefer, G. HSturmann, JSturmann, Laszloten Brummelaar, TheoTurner, Nils2015-12-101745-3933http://hdl.handle.net/1885/66577We present long-baseline interferometry of the Kepler exoplanet host star HD179070 (Kepler-21) using the Precision Astronomical Visible Observations (PAVO) beam combiner at the Center for High Angular Resolution Astronomy (CHARA) Array. The visibility data are consistent with a single star and exclude stellar companions at separations ~1-1000 mas (~0.1-113 au) and contrasts <3.5 mag. This result supports the validation of the 1.6R⊕ exoplanet Kepler-21b by Howell et al. and complements the constraints set by adaptive optics imaging, speckle interferometry and radial-velocity observations to rule out false positives due to stellar companions. We conclude that long-baseline interferometry has strong potential to validate transiting extrasolar planets, particularly for future projects aimed at brighter stars and for host stars where radial-velocity follow-up is not available.Author/s retain copyrightKeywords: Planets and satellites: individual: Kepler-2lb; Stars: individual: HD 179070; Techniques: interferometric201210.1111/j.1745-3933.2012.01242.x2016-02-24