KELT-7b: A Hot Jupiter Transiting a Bright V = 8.54 Rapidly Rotating F-Star

Creators: Bieryla, Allyson; Fulton, Benjamin J.

Abstract

We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of 1.28 ± 0.18 MJ, radius of 1.533^(+0.046)_(-0.047) R_J, and an orbital period of 2.7347749 ± 0.0000039 days. The bright host star (HD 33643; KELT-7) is an F-star with V = 8.54, T_(eff) = 6789^(+50)_(-49)K, [Fe/H] = 0.139^(+0.075)_(-0.081), and log g = 4.149 ± 0.019. It has a mass of 1.535^(+0.066)_(-0. 054) M⊙, a radius of 1.732^(+0.043)_(-0.045) R⊙, and is the fifth most massive, fifth hottest, and the ninth brightest star known to host a transiting planet. It is also the brightest star around which Kilodegree Extremely Little Telescope (KELT) has discovered a transiting planet. Thus, KELT-7b is an ideal target for detailed characterization given its relatively low surface gravity, high equilibrium temperature, and bright host star. The rapid rotation of the star (73 ± 0.5 km s^(−1)) results in a Rossiter–McLaughlin effect with an unusually large amplitude of several hundred m s−1. We find that the orbit normal of the planet is likely to be well-aligned with the stellar spin axis, with a projected spin–orbit alignment of λ = 9 7 ± 5 2. This is currently the second most rapidly rotating star to have a reflex signal (and thus mass determination) due to a planetary companion measured.

Additional Information

© 2015 The American Astronomical Society. Received 2015 January 16; accepted 2015 May 6; published 2015 June 18. This paper uses observations obtained with facilities of the Las Cumbres Observatory Global Telescope. The Byrne Observatory at Sedgwick (BOS) is operated by the Las Cumbres Observatory Global Network and is located at the Sedgwick Reserve, as part of the University of California Natural Reserve System. Early work on KELT-North was supported by NASA Grant NNG04GO70G. A.B. acknowledges partial support from the Kepler mission under Cooperative Agreement NNX13AB58A with the Smithsonian Astrophysical Observatory, D.W.L. PI. B.J.F. acknowledges that this material is based on work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 2014184874. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. R.S.O. acknowledges that this work was performed in part under contract with the California Institute of Technology (Caltech)/Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. K.G.S. acknowledges support from the Vanderbilt Office of the Provost through the Vanderbilt Initiative in Data-intensive Astrophysics and the support of the National Science Foundation through PAARE Grant AST-1358862. Work by B.S.G. and T.G.B. was partially supported by NSF CAREER Grant AST-1056524. Work by J.N.W. was supported by the NASA Origins program under grant NNX11AG85G. The authors would like to thank the KELT partners, Mark Manner, Roberto Zambelli, Phillip Reed, Valerio Bozza, that have contributed to the project and Iain McDonald for his conversations about the data regarding the IR excess detected in the SED analysis. This work has made use of NASA Astrophysics Data System, the Exoplanet Orbit Database at exoplanets.org, the Extrasolar Planet Encyclopedia at exoplanet.eu (Schneider 2011), the SIMBAD database operated at CDS, Strasbourg, France, and Systemic (Meschiari et al. 2009).

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