EPIC 246851721 b: A Tropical Jupiter Transiting a Rapidly Rotating Star in a Well-aligned Orbit

Yu, Liang and Zhou, George ORCID: https://orcid.org/0000-0002-4891-3517 and Rodriguez, Joseph E. and Huang, Chelsea X. ORCID: https://orcid.org/0000-0003-0918-7484 and Vanderburg, Andrew and Quinn, Samuel N. and Gaudi, B. Scott and Beichman, Charles A. and Berlind, Perry and Bieryla, Allyson and Calkins, Michael L. and Ciardi, David R. and Crossfield, Ian J. M. and Eastman, Jason D. and Esquerdo, Gilbert A. and Latham, David W. and Stassun, Keivan G. and Villanueva, Steven, Jr. (2018) EPIC 246851721 b: A Tropical Jupiter Transiting a Rapidly Rotating Star in a Well-aligned Orbit. The Astronomical Journal, 156 (6):250. pp. 1-13. ISSN 0004-6256

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We report the discovery of EPIC 246851721 b, a 'tropical' Jupiter in a 6.18-day orbit around the bright (V = 11.439) star EPIC 246851721 (TYC 1283-739-1). We present a detailed analysis of the system using K2 and ground-based photometry, radial velocities, Doppler tomography, and adaptive optics imaging. From our global models, we infer that the host star is a rapidly rotating (nu sin I-* = 74.92 km s(-1)) F dwarf with T-eff = 6202 K, R-* = 1.586 R-circle dot and M-* = 1.317 M-circle dot. EPIC 246851721 b has a radius of 1.051 +/- 0.044 R-J, and a mass of 3.0(-1.2)(+1.1) M-J. Doppler tomography reveals an aligned spin-orbit geometry, with a projected obliquity of -1.degrees 47(-0.86)(+0.87), making EPIC 246851721 the fourth hottest star to host a Jovian planet with P > 5 days and a known obliquity. Using quasi-periodic signatures in its light curve that appear to be spot modulations, we estimate the star's rotation period, and thereby infer the true obliquity of the system to be 3.degrees 7(-1.8)(+3.7). We argue that this near-zero obliquity is likely to be primordial rather than a result of tidal damping. The host star also has a bound stellar companion, a 0.4 M-circle dot M dwarf at a projected separation of 2100 au, but the companion is likely incapable of emplacing EPIC 246851721 b in its current orbit via high-eccentricity Kozai-Lidov migration.

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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 23:29
Last Modified: 01 Mar 2022 01:53
Uncontrolled Keywords: planetary systems; planets and satellites: detection; stars: individual (EPIC 246851721); 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
Identification Number or DOI: https://doi.org/10.3847/1538-3881/aae5d5
URI: http://eprints.usq.edu.au/id/eprint/45037

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