LHS 6343 C: A Transiting Field Brown Dwarf Discovered by the Kepler Mission

Creators: Johnson, John Asher; Apps, Kevin; Gazak, J. Zachary; Crepp, Justin R.; Crossfield, Ian J.; Howard, Andrew W.; Marcy, Geoff W.; Morton, Timothy D.; Chubak, Carly; Isaacson, Howard

Abstract

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.

Additional Information

© 2011 American Astronomical Society. Received 2010 September 8; accepted 2011 January 18; published 2011 March 8. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by Caltech, the University of California, and NASA. We thank Keivan Stassun and Leslie Hebb for providing us with their B and V photometry of the LHS 6343 system. We thank Jonathan Irwin for his independent analysis of the Kepler light curve and for encouraging us to incorporate the third-light correction into our forward-modeling procedure; Josh Carter for independently confirming our best-fitting light curve parameters; and John Gizis for pointing out an error in our calculation of the brown dwarf mass in an earlier draft of this manuscript. We gratefully acknowledge the tireless dedication and hard work of the Kepler team, without whom this project would not be possible. In particular, we thank Jon Jenkins and Lucianne Walkowicz for confirming the planet-like nature of the transits following the initial identification of transit events by K.A. We gratefully acknowledge the efforts and dedication of the Keck Observatory staff, especially Grant Hill, Scott Dahm, and Hien Tran for their support of HIRES and Greg Wirth for support of remote observing. We made use of the SIMBAD database operated at CDS, Strasbourge, France, and NASA's Astrophysics Data System Bibliographic Services. A.W.H. gratefully acknowledges support from a Townes Post-doctoral Fellowship at the U.C. Berkeley Space Sciences Laboratory. G.W.M. acknowledges NASA grant NNX06AH52G. Finally, we extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible.

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