Abstract
We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright (V ∼ 9.9) A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial velocities, which limit the mass to ≳4.1 MJ (3s), and a clear Doppler tomography signal, which indicates a retrograde projected spin-orbit misalignment of λ = -179.7-3.8 +3.7 degrees. Global modeling indicates that the Teff = 7500 ±110 K host star has M M = 1.62+0.20 -0.25 and R = 1.83 0.10 R. The planet has a radius of RP = 1.91 0.11 RJ and receives a stellar insolation flux of ∼ 3.2 10 erg s-1 cm-2, leading to an inferred equilibrium temperature of Teq ∼ 1935 K assuming zero albedo and complete heat redistribution. With a v I sin 84.8 ±2.0 km s = -1, the host is relatively slowly rotating compared to other stars with similar effective temperatures, and it appears to be enhanced in metallic elements but deficient in calcium, suggesting that it is likely an Am star. KELT-19A would be the first detection of an Am host of a transiting planet of which we are aware. Adaptive optics observations of the system reveal the existence of a companion with late-G9V/early-K1V spectral type at a projected separation of »160 au. Radial velocity measurements indicate that this companion is bound. Most Am stars are known to have stellar companions, which are often invoked to explain the relatively slow rotation of the primary. In this case, the stellar companion is unlikely to have caused the tidal braking of the primary. However, it may have emplaced the transiting planetary companion via the Kozai-Lidov mechanism.
| Original language | English |
|---|---|
| Article number | 35 |
| Journal | Astronomical Journal |
| Volume | 155 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2018 |
Funding
The David & Lucile Packard Foundation, National Aeronautics and Space Administration (EPSCOR grant NNX13AM97A), The Australian Research Council (LIEF grant LE140100050), and the National Science Foundation (grants 1516242 and 1608203). 1Las Cumbres Observatory, 6740 Cortona Drive, Suite 102, Goleta, CA 93117, USA 2Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA; [email protected] 3Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA 4Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235, USA 5Department of Physics, Fisk University, 1000 17th Avenue North, Nashville, TN 37208, USA 6NASA Exoplanet Science Institute/Caltech, Pasadena, CA, USA 7Department of Physics, The University of Texas at Dallas, 800 West Campbell Road, Richardson, TX 75080-3021, USA 8Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA, 18015, USA 9Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA 10Atalaia Group & CROW Observatory, Portalegre, Portugal 11Department of Physics, Westminster College, New Wilmington, PA 16172, USA 12Dipartimento di Fisica “E. R. Caianiello,” Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (SA), Italy 13Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, I-80126 Napoli, Italy 14Division of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA 15Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA 16IPAC, Mail Code 100-22, Caltech, 1200 E. California Boulevard, Pasadena, CA 91125, USA 17Department of Astronomy & Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 18Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802, USA 19South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 Cape Town, South Africa 20Southern African Large Telescope, P.O. Box 9, Observatory, 7935 Cape Town, South Africa 21NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 22Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195, USA 23Department of Physics and Astronomy, University of Montana, Missoula, MT 59812, USA 24University of Southern Queensland, Computational Engineering and Science Research Centre, Toowoomba, Queensland 4350, Australia 25Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 26Department of Physics and Astronomy, Swarthmore College, Swarthmore, PA 19081, USA 27Department of Astronomy, Wellesley College, Wellesley, MA 02481, USA 28Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602, USA 29Società Astronomica Lunae, Castelnuovo Magra I-19030, Italy 30Hazelwood Observatory, Churchill, Victoria, Australia 31El Sauce Observatory, Coquimbo Province, Chile 32Perth Exoplanet Survey Telescope, Perth, Australia 33ICO, Adelaide, South Australia 34Department of Physical Sciences, Kutztown University, 15200 Kutztown Road, Kutztown, PA, 19530, USA 35Winer Observatory, 22 Milky Way, Sonoita, AZ 85637, USA
| Funders | Funder number |
|---|---|
| Kutztown University | |
| 1056524, 1343012 | |
| National Aeronautics and Space Administration | NNX13AM97A |
| Wellesley College | |
| NASA Goddard Space Flight Center | |
| Vanderbilt University | |
| Bloomsburg University of Pennsylvania | |
| Ohio State University | |
| California Institute of Technology | |
| University of California at Berkeley | 100-22 |
| University of Louisville | |
| Lehigh University | |
| Pennsylvania State University | |
| Australian Research Council | LE140100050 |
| 1516242, 1608203 | |
| Brigham Young University |
Keywords
- methods: observational
- planets and satellites: detection
- planets and satellites: gaseous planets
- techniques: photometric
- techniques: radial velocities
- techniques: spectroscopic