Kelt-4Ab: An inflated hot jupiter transiting the bright (V ∼ 10) component of a hierarchical triple

Jason D. Eastman, Thomas G. Beatty, Robert J. Siverd, Joseph M.O. Antognini, Matthew T. Penny, Erica J. Gonzales, Justin R. Crepp, Andrew W. Howard, Ryan L. Avril, Allyson Bieryla, Karen Collins, Benjamin J. Fulton, Jian Ge, Joao Gregorio, Bo Ma, Samuel N. Mellon, Thomas E. Oberst, Ji Wang, B. Scott Gaudi, Joshua PepperKeivan G. Stassun, Lars A. Buchhave, Eric L.N. Jensen, David W. Latham, Perry Berlind, Michael L. Calkins, Phillip A. Cargile, Knicole D. Colón, Saurav Dhital, Gilbert A. Esquerdo, John Asher Johnson, John F. Kielkopf, Mark Manner, Qingqing Mao, Kim K. McLeod, Kaloyan Penev, Robert P. Stefanik, Rachel Street, Roberto Zambelli, D. L. DePoy, Andrew Gould, Jennifer L. Marshall, Richard W. Pogge, Mark Trueblood, Patricia Trueblood

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


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.

Original languageEnglish (US)
Article number45
JournalAstronomical Journal
Issue number2
StatePublished - Feb 1 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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