• techniques: interferometric;
  • planets and satellites: individual: Kepler-2lb;
  • stars: individual: HD 179070


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 ∼1–1000 mas (∼0.1–113 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.