KELT-20b: A Giant Planet with a Period of P ∼ 3.5 days Transiting the V ∼ 7.6 Early A Star HD 185603

Lund, Michael B. and Rodriguez, Joseph E. and Zhou, George ORCID: and Gaudi, B. Scott and Stassun, Keivan G. and Johnson, Marshall C. and Bieryla, Allyson and Oelkers, Ryan J. and Stevens, Daniel J. and Collins, Karen A. and Penev, Kaloyan and Quinn, Samuel N. and Latham, David W. and Villanueva, Steven, Jr. and Eastman, Jason D. and Kielkopf, John F. and Oberst, Thomas E. and Jensen, Eric L. N. and Cohen, David H. and Joner, Michael D. and Stephens, Denise C. and Relles, Howard and Corfini, Giorgio and Gregorio, Joao and Zambelli, Roberto and Esquerdo, Gilbert A. and Calkins, Michael L. and Berlind, Perry and Ciardi, David R. and Dressing, Courtney and Patel, Rahul and Gagnon, Patrick and Gonzales, Erica and Beatty, Thomas G. and Siverd, Robert J. and Labadie-Bartz, Jonathan and Kuhn, Rudolf B. and Colon, Knicole D. and James, David and Pepper, Joshua and Fulton, Benjamin J. and McLeod, Kim K. and Stockdale, Christopher and Calchi Novati, Sebastiano and DePoy, D. L. and Gould, Andrew and Marshall, Jennifer L. and Trueblood, Mark and Trueblood, Patricia and Johnson, John A. and Wright, Jason and McCrady, Nate and Wittenmyer, Robert A. and Johnson, Samson A. and Sergi, Anthony and Wilson, Maurice and Sliski, David H. (2017) KELT-20b: A Giant Planet with a Period of P ∼ 3.5 days Transiting the V ∼ 7.6 Early A Star HD 185603. The Astronomical Journal, 154 (5):194. pp. 1-16. ISSN 0004-6256

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We report the discovery of KELT-20b, a hot Jupiter transiting a V ∼7.6 early A star, HD 185603, with an orbital period of P ≃3.47 days. Archival and follow-up photometry, Gaia parallax, radial velocities, Doppler tomography, and AO imaging were used to confirm the planetary nature of KELT-20b and characterize the system. From global modeling we infer that KELT-20 is a rapidly rotating (v sin I∗ ≃ 120 km s-1 ) A2V star with an effective temperature of Teff=8730 -260 +250 K, mass of M∗+1.76-0.20 +0.14MO, radius of R∗= 1.561-0.064+0.058RO,surface gravity of log g ∗=4.292-0.020+0.017, and age of ≳600 Myr. The planetary companion has a radius of Rp=1.735 -0.075 +0.070Rj, a semimajor axis of a =0.0542-0.0021+0.0014 au, and a linear ephemeris of BJDTDB=2457503.120049 ± 0.000190+E(3.4741070± 0.0000019). We place a 3s upper limit of ∼ 3.5 MJ on the mass of the planet. Doppler tomographic measurements indicate that the planetary orbit normal is well aligned with the projected spin axis of the star (l = 3 °.4± 2 °.1). The inclination of the star is constrained to 24°.4 > I ∗ > 155 °.6, implying a three-dimensional spin-orbit alignment of 1°.3 > ψ > 69°.8. KELT-20b receives an insolation flux of∼8× 109 erg s-1cm-2, implying an equilibrium temperature of of ∼ 2250 K, assuming zero albedo and complete heat redistribution. Due to the high stellar Teff, KELT-20b also receives an ultraviolet (wavelength d ≤ 91.2 nm) insolation flux of ∼9.1×104erg s-1 cm-2, possibly indicating significant atmospheric ablation. Together with WASP-33, Kepler-13 A, HAT-P-57, KELT-17, and KELT-9, KELT-20 is the sixth A star host of a transiting giant planet, and the third brightest host (in V) of a transiting planet.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 08 Feb 2022 03:02
Last Modified: 04 Apr 2022 07:52
Uncontrolled Keywords: methods: observational; planets and satellites: detection; planets; and satellites: gaseous planets; stars: individual (HD 185603); techniques: photometric; techniques: radial velocities; Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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