Jason D. Eastman, Harvard-Smithsonian Center for Astrophysics
Thomas G. Beatty, Pennsylvania State University
Robert J. Siverd, Las Cumbres Observatory Global Telescope Network, Inc
Joseph M.O. Antognini, The Ohio State University
Matthew T. Penny, The Ohio State University
Erica J. Gonzales, University of Notre Dame
Justin R. Crepp, University of Notre Dame
Andrew W. Howard, University Hawaii Institute for Astronomy
Ryan L. Avril, Westminster College, New Wilmington
Allyson Bieryla, Harvard-Smithsonian Center for Astrophysics
Karen Collins, Vanderbilt University
Benjamin J. Fulton, University Hawaii Institute for Astronomy
Jian Ge, University of Florida
Joao Gregorio, Atalaia Group and CROW Observatory
Bo Ma, University of Florida
Samuel N. Mellon, Westminster College, New Wilmington
Thomas E. Oberst, Westminster College, New Wilmington
Ji Wang, California Institute of Technology
B. Scott Gaudi, The Ohio State University
Joshua Pepper, Lehigh University
Keivan G. Stassun, Vanderbilt University
Lars A. Buchhave, Harvard-Smithsonian Center for Astrophysics
Eric L.N. Jensen, Swarthmore College
David W. Latham, Harvard-Smithsonian Center for Astrophysics
Perry Berlind, Harvard-Smithsonian Center for Astrophysics
Michael L. Calkins, Harvard-Smithsonian Center for Astrophysics
Phillip A. Cargile, Harvard-Smithsonian Center for Astrophysics
Knicole D. Colón, Lehigh University
Saurav Dhital, Boston University
Gilbert A. Esquerdo, Harvard-Smithsonian Center for Astrophysics
John Asher Johnson, Harvard-Smithsonian Center for Astrophysics
John F. Kielkopf, University of Louisville
Mark Manner, Spot Observatory

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We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of ahierarchical triple stellar system. The host star is an F star with Teff =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 BJDTDB =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 RJ, and a mass of 0.902-0.059+0.060 MJ, it is the brightest host among the population of inflated Hot Jupiters (RP > 1.5RJ), 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.

Publication Source (Journal or Book title)

Astronomical Journal