2011ApJ...730...79J

We report the discovery of a brown dwarf that transits one member of the M+M binary system LHS 6343 AB every 12.71 days. The transits were discovered using photometric data from the Kepler public data release. The LHS 6343 stellar system was previously identified as a single high proper motion M dwarf. We use adaptive optics imaging to resolve the system into two low-mass stars with masses 0.370±0.009 M_☉ and 0.30±0.01 M_☉, respectively, and a projected separation of 0".55. High-resolution spectroscopy shows that the more massive component undergoes Doppler variations consistent with Keplerian motion, with a period equal to the transit period and an amplitude consistent with a companion mass of M_C= 62.7±2.4 M_Jup. Based on our analysis of the transit light curve, we estimate the radius of the companion to be R_C= 0.833±0.021 R_Jup, which is consistent with theoretical predictions of the radius of a >1 Gyr brown dwarf.