KELT-4Ab: An inflated Hot Jupiter transiting the bright (V~10) component of a hierarchical triple

Creators: Eastman, Jason D.; Howard, Andrew W.; Wang, Ji; Fulton, Benjamin J.

Abstract

We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with T_(eff) = 6206 ± 75 K, log g = 4.108 ± 0.014, [Fe/H] = -0.116_(-0.069)^(+0.065, M_* = 1.201_(-0.061)^(+0.067) M_☉, and R_* = 1.603_(-0.038)^(+0.039) R_☉. The best-fit linear ephemeris is BJD_(TDB); = 2456193.29157 ± 0.00021 + E(2.9895936 ± 0.0000048). With a magnitude of V ~ 10, a planetary radius of 1.699_(-0.045)^(+0.046); R_J, and a mass of 0.902_(-0.059)^(+0.060) M_J, it is the brightest host among the population of inflated Hot Jupiters (R_P > 1.5 R_J), making it a valuable discovery for probing the nature of inflated planets. In addition, its existence within a hierarchical triple and its proximity to Earth (210 pc) provide a unique opportunity for dynamical studies with continued monitoring with high resolution imaging and precision radial velocities. The projected separation between KELT-4A and KELT-4BC is 328 ± 16 AU and the projected separation between KELT-4B and KELT-4C is 10.30 ± 0.74 AU. Assuming face-on, circular orbits, their respective periods would be 3780 ± 290 and 29.4 ± 3.6 years and the astrometric motions relative to the epoch in this work of both the binary stars around each other and of the binary around the primary star would be detectable now and may provide meaningful constraints on the dynamics of the system.

Additional Information

© 2016 American Astronomical Society. Received 2015 September 30; accepted 2015 November 20; published 2016 February 4. 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. Early work on KELT-North was supported by NASA Grant NNG04GO70G. Work by B.S.G., J.D.E., and T.G.B. was partially supported by NSF CAREER Grant AST-1056524. K.A.C. was supported by a NASA Kentucky Space Grant Consortium Graduate Fellowship. J.A.P. and K.G.S. acknowledge support from the Vanderbilt Office of the Provost through the Vanderbilt Initiative in Data-intensive Astrophysics. K.G.S. and L.H. acknowledge the support of the National Science Foundation through PAARE grant AST-0849736 and AAG grant AST-1009810. The TRES and KeplerCam observations were obtained with partial support from the Kepler Mission through NASA Cooperative Agreement NNX11AB99A with the Smithsonian Astrophysical Observatory, D.W.L. PI. J.M.O.A. is supported in part by NSF Award #1313252. J.G., B.M., and J.W. acknowledge support from NSF AST-0705139 and the University of Florida for the development of the EXPERT instrument and observations. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under grant No. 2014184874. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors(s) and do not necessarily reflect the views of the National Science Foundation. The Byrne Observatory at Sedgwick (BOS) is operated by the Las Cumbres Observatory Global Telescope Network and is located at the Sedgwick Reserve, a part of the University of California Natural Reserve System. This work makes use of observations from the LCOGT network. This work has made use of NASA's Astrophysics Data System, the Extrasolar Planet Encyclopedia at exoplanet.eu (Schneider et al. 2011), the SIMBAD database operated at CDS, Strasbourg, France, and the VizieR catalogue access tool, CDS, Strasbourg, France (Ochsenbein et al. 2000). Certain calculations in this paper were carried out on the Ruby cluster operated by the Ohio Supercomputer Center (Center 2015). This publication makes use of data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This paper makes use of data from the first public release of the WASP data (Butters et al. 2010) as provided by the WASP consortium and services at the NASA Exoplanet Archive (Akeson et al. 2013), which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program, the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org (Wright et al. 2011).

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