KELT-6b: A P ∼ 7.9 day hot Saturn transiting a metal-poor star with a long-period companion
- Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292 (United States)
- Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States)
- Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States)
- Department of Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
- Department of Astronomy, Yale University, New Haven, CT 06511 (United States)
- Spot Observatory, Nunnelly, TN 37137 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Atalaia Group and Crow-Observatory, Portalegre (Portugal)
- Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-21S00 Copenhagen (Denmark)
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081 (United States)
- Princeton University, Princeton, NJ 08544 (United States)
- Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
We report the discovery of KELT-6b, a mildly inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V = 10.38 host star (BD+31 2447) is a mildly evolved, late-F star with T {sub eff} = 6102 ± 43 K, log g{sub ⋆}=4.07{sub −0.07}{sup +0.04}, and [Fe/H] = –0.28 ± 0.04, with an inferred mass M {sub *} = 1.09 ± 0.04 M {sub ☉} and radius R{sub ⋆}=1.58{sub −0.09}{sup +0.16} R{sub ⊙}. The planetary companion has mass M{sub P} = 0.43 ± 0.05 M {sub Jup}, radius R{sub P}=1.19{sub −0.08}{sup +0.13} R{sub Jup}, surface gravity log g{sub P}=2.86{sub −0.08}{sup +0.06}, and density ρ{sub P}=0.31{sub −0.08}{sup +0.07} g cm{sup −3}. The planet is on an orbit with semimajor axis a = 0.079 ± 0.001 AU and eccentricity e=0.22{sub −0.10}{sup +0.12}, which is roughly consistent with circular, and has ephemeris of T {sub c}(BJD{sub TDB}) = 2456347.79679 ± 0.00036 and P = 7.845631 ± 0.000046 days. Equally plausible fits that employ empirical constraints on the host-star parameters rather than isochrones yield a larger planet mass and radius by ∼4)-7). KELT-6b has surface gravity and incident flux similar to HD 209458b, but orbits a host that is more metal poor than HD 209458 by ∼0.3 dex. Thus, the KELT-6 system offers an opportunity to perform a comparative measurement of two similar planets in similar environments around stars of very different metallicities. The precise radial velocity data also reveal an acceleration indicative of a longer-period third body in the system, although the companion is not detected in Keck adaptive optics images.
- OSTI ID:
- 22340014
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 147, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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