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. Stevens; Roberto 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

doi:10.1088/0004-637X/810/1/30

paper

KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

arXiv:1505.06738 · doi:10.1088/0004-637X/810/1/30

Abstract

We announce the discovery of a highly inflated transiting hot Jupiter discovered 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 $T_{eff} = 575 4_{- 55}^{+ 54}$ K, $lo g g = 4.07 8_{- 0.054}^{+ 0.049}$ , $[F e / H] = 0.272 \pm 0.038$ , an inferred mass $M_{*} = 1.21 1_{- 0.066}^{+ 0.078}$ M $_{⊙}$ , and radius $R_{*} = 1.6 7_{- 0.12}^{+ 0.14}$ R $_{⊙}$ . The planetary companion has mass $M_{P} = 0.86 7_{- 0.061}^{+ 0.065}$ $M_{J}$ , radius $R_{P} = 1.8 6_{- 0.16}^{+ 0.18}$ $R_{J}$ , surface gravity $lo g g_{P} = 2.79 3_{- 0.075}^{+ 0.072}$ , and density $ρ_{P} = 0.16 7_{- 0.038}^{+ 0.047}$ g cm $^{- 3}$ . The planet is on a roughly circular orbit with semimajor axis $a = 0.0457 1_{- 0.00084}^{+ 0.00096}$ AU and eccentricity $e = 0.03 5_{- 0.025}^{+ 0.050}$ . The best-fit linear ephemeris is $T_{0} = 2456883.4803 \pm 0.0007$ BJD $_{TDB}$ and $P = 3.24406 \pm 0.00016$ 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 $lo g g$ and large implied radius are supported by stellar density constraints from follow-up light curves, plus 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 $T_{e q} = 167 5_{- 55}^{+ 61}$ K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.

Submitted to ApJ, feedback is welcome

KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

Abstract

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