KELT-8b: A HIGHLY INFLATED TRANSITING HOT JUPITER AND A NEW TECHNIQUE FOR EXTRACTING HIGH-PRECISION RADIAL VELOCITIES FROM NOISY SPECTRA

Benjamin J. Fulton, Karen A. Collins, B. Scott Gaudi, Keivan G. Stassun, Joshua Pepper, Thomas G. Beatty, Robert J. Siverd, Kaloyan Penev, Andrew W. Howard, Christoph Baranec, Giorgio Corfini, Jason D. Eastman, Joao Gregorio, Nicholas M. Law, Michael B. Lund, Thomas E. Oberst, Matthew T. Penny, Reed Riddle, Joseph E. Rodriguez, Daniel J. StevensRoberto Zambelli, Carl Ziegler, Allyson Bieryla, Giuseppe D'Ago, Darren L. DePoy, Eric L.N. Jensen, John F. Kielkopf, David W. Latham, Mark Manner, Jennifer Marshall, Kim K. McLeod, Phillip A. Reed

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

We announce the discovery of a highly inflated transiting hot Jupiter by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with Teff = 5754-55+54 K, log g = 4.078-0.054+0.049, [Fe/H] = 0.272 ± 0.038, an inferred mass M = 1.211 -0.066+0.078 M, and radius R = 1.67-0.12+0.14 R. The planetary companion has a mass MP = 0.867-0.061+0.065 MJ, radius RP = 1.86-0.16+0.18 RJ, surface gravity log gP = 2.793-0.075+0.072, and density ρP = 0.167-0.038+0.047 g cm-3. The planet is on a roughly circular orbit with semimajor axis a = 0.04571-0.00084+0.00096 AU and eccentricity e = 0.035-0.025+0.050. The best-fit linear ephemeris is T0 = 2456883.4803 ± 0.0007 BJDTDB and P = 3.24406 ± 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly irradiated gas giants. The low stellar log g and large implied radius are supported by stellar density constraints from follow-up light curves, as well as an evolutionary and space motion analysis. We also develop a new technique to extract high-precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of Teq = 1675-55+61 K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.

Original languageEnglish (US)
Article number30
JournalAstrophysical Journal
Volume810
Issue number1
DOIs
StatePublished - Sep 1 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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