We report the discovery of a brown dwarf that transits one member of the M+M binary system LHS6343AB every 12.71 days. The transits were discovered using photometric data from the Kelper public data release. The LHS6343 stellar system was previously identified as a single high-proper-motion M dwarf. We use high-contrast imaging to resolve the system into two low-mass stars with masses 0.45 Msun and 0.36 Msun, respectively, and a projected separation of 55 arcsec. 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 = 62.8 +/- 2.3 Mjup. Based on an analysis of the Kepler light curve we estimate the radius of the companion to be R_C = 0.832 +/- 0.021 Rjup, which is consistent with theoretical predictions of the radius of a > 1 Gyr brown dwarf.
@article{arxiv.1008.4141,
title = {LHS6343C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission},
author = {John Asher Johnson and Kevin Apps and J. Zachary Gazak and Justin R. Crepp and Ian J. Crossfield and Andrew W. Howard and Geoff W. Marcy and Timothy D. Morton and Carly Chubak and Howard Isaacson},
journal= {arXiv preprint arXiv:1008.4141},
year = {2015}
}
Comments
Our previous analysis neglected the dependence of the scaled semimajor axis, a/R, on the transit depth. By not correcting a/R for the third-light contamination, we overestimated the mass of Star A, which led to an overestimate the mass and radius of the LHS6343C