Validation of the exoplanet Kepler-21b using PAVO/CHARA long-baseline interferometry

We present long-baseline interferometry of the Kepler exoplanet host star HD 179070 (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 similar to 11000 mas (similar to 0.1113 au) and contrasts <3.5 mag. This result supports the validation of the 1.6 R ? 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.