KELT-22Ab: A Massive, Short-Period Hot Jupiter Transiting a Near-solar Twin

Creators: Labadie-Bartz, Jonathan; Ciardi, David R.; Fulton, Benjamin J.

Abstract

We present the discovery of KELT-22Ab, a hot Jupiter from the KELT-South survey. KELT-22Ab transits the moderately bright (V∼11.1) Sun-like G2V star TYC 7518-468-1. The planet has an orbital period of P = 1.3866529±0.0000027 days, a radius of R_P = 1.285^(+0.12)_(−0.071) R_J, and a relatively large mass of M_P = 3.47^(+0.15)_(−0.14) M_J. The star has R⋆ = 1.099^(+0.079)_(−0.046) R⊙, M⋆ = 1.092^(+0.045)_(−0.041) M⊙, T_(eff) = 5767^(+50)_(−49) K, log g⋆ = 4.393^(+0.039)_(−0.060) (cgs), and [m/H] = +0.259^(+0.085)_(−0.083), and thus, other than its slightly super-solar metallicity, appears to be a near solar twin. Surprisingly, KELT-22A exhibits kinematics and a Galactic orbit that are somewhat atypical for thin disk stars. Nevertheless, the star is rotating quite rapidly for its estimated age, shows evidence of chromospheric activity, and is somewhat metal rich. Imaging reveals a slightly fainter companion to KELT-22A that is likely bound, with a projected separation of 6" (∼1400 AU). In addition to the orbital motion caused by the transiting planet, we detect a possible linear trend in the radial velocity of KELT-22A suggesting the presence of another relatively nearby body that is perhaps non-stellar. KELT-22Ab is highly irradiated (as a consequence of the small semi-major axis of a/R⋆ = 4.97), and is mildly inflated. At such small separations, tidal forces become significant. The configuration of this system is optimal for measuring the rate of tidal dissipation within the host star. Our models predict that, due to tidal forces, the semi-major axis of KELT-22Ab is decreasing rapidly, and is thus predicted to spiral into the star within the next Gyr.

Additional Information

© 2019 The American Astronomical Society. Received 2018 March 19; revised 2018 October 11; accepted 2018 October 16; published 2019 January 21. This project makes use of data from the KELT survey, including support from The Ohio State University, Vanderbilt University, and Lehigh University, along with the KELT follow-up collaboration. J.L.-B. acknowledges support from FAPESP (grant 2017/23731-1). Work performed by J.E.R. was supported by the Harvard Future Faculty Leaders Postdoctoral fellowship. D.W.L. acknowledges partial support under NASA Cooperative Agreement NNX13AB58A with the Smithsonian Astrophysical Observatory. D.J.S. and B.S.G. were partially supported by NSF CAREER grant AST-1056524. D.J.J. gratefully acknowledges support from National Science Foundation award NSF-1440254. Work by S.V.Jr. is supported by the National Science Foundation Graduate Research Fellowship under grant No. DGE-1343012 and the David G. Price Fellowship in Astronomical Instrumentation. Work by G.Z. is provided by NASA through Hubble Fellowship grant HST-HF2-51402.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. This work has made use of NASA's Astrophysics Data System, the Extrasolar Planet Encyclopedia, the NASA Exoplanet Archive, the SIMBAD database operated at CDS, Strasbourg, France, and the VizieR catalog access tool, CDS, Strasbourg, France. We also used data products from the Widefield Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles; the Jet Propulsion Laboratory/California Institute of Technology, which is funded by the National Aeronautics and Space Administration; 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; and the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. MINERVA is a collaboration among the Harvard-Smithsonian Center for Astrophysics, The Pennsylvania State University, the University of Montana, and the University of New South Wales. MINERVA is made possible by generous contributions from its collaborating institutions and Mt. Cuba Astronomical Foundation, The David & Lucile Packard Foundation, National Aeronautics and Space Administration (EPSCOR grant NNX13AM97A), The Australian Research Council (LIEF grant LE140100050), and the National Science Foundation (grants 1516242 and 1608203). The Center for Exoplanets and Habitable Worlds is supported by the Pennsylvania State University, the Eberly College of Science, and the Pennsylvania Space Grant Consortium. Any opinions, findings, and conclusions or recommendations expressed are those of the author and do not necessarily reflect the views of the National Science Foundation. The authors thank Andrew Collier Cameron and Nevin N. Weinberg for helpful discussion regarding the role of tidal forces in the KELT-22A system, and the anonymous referee for comments that improved this manuscript. Facilities: KELT - , - FLWO (TRES) - , Keck (NIRC2) - , ANU:2.3 m (WiFeS) - , LCO. - Software: Python, IDL, IRAF, TAPIR (Jensen 2013), AstroImageJ (Collins & Kielkopf 2013), EXOFAST (Eastman et al. 2013), POET (Penev et al. 2014), galpy (Bovy 2015), VARTOOLS (Hartman 2012).

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