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The Possible Tidal Demise of Kepler's First Planetary System

Vissapragada, Shreyas and Chontos, Ashley and Greklek-McKeon, Michael and Knutson, Heather A. and Dai, Fei and González, Jorge Pérez and Grunblatt, Sam and Huber, Daniel and Saunders, Nicholas (2022) The Possible Tidal Demise of Kepler's First Planetary System. Astrophysical Journal Letters, 941 (2). Art. No. L31. ISSN 2041-8205. doi:10.3847/2041-8213/aca47e.

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We present evidence of tidally-driven inspiral in the Kepler-1658 (KOI-4) system, which consists of a giant planet (1.1R_J, 5.9M_J) orbiting an evolved host star (2.9R_⊙, 1.5M_⊙). Using transit timing measurements from Kepler, Palomar/WIRC, and TESS, we show that the orbital period of Kepler-1658b appears to be decreasing at a rate Ṗ = 131⁺²⁰₋₂₂ ms yr⁻¹, corresponding to an infall timescale P/Ṗ ≈ 2.5 Myr. We consider other explanations for the data including line-of-sight acceleration and orbital precession, but find them to be implausible. The observed period derivative implies a tidal quality factor Q'_* = 2.50⁺⁰·⁸⁵₋₀.₆₂ × 10⁴, in good agreement with theoretical predictions for inertial wave dissipation in subgiant stars. Additionally, while it probably cannot explain the entire inspiral rate, a small amount of planetary dissipation could naturally explain the deep optical eclipse observed for the planet via enhanced thermal emission. As the first evolved system with detected inspiral, Kepler-1658 is a new benchmark for understanding tidal physics at the end of the planetary life cycle.

Item Type:Article
Related URLs:
URLURL TypeDescription
Vissapragada, Shreyas0000-0003-2527-1475
Chontos, Ashley0000-0003-1125-2564
Greklek-McKeon, Michael0000-0002-0371-1647
Knutson, Heather A.0000-0002-5375-4725
Dai, Fei0000-0002-8958-0683
González, Jorge Pérez0000-0001-7144-589X
Grunblatt, Sam0000-0003-4976-9980
Huber, Daniel0000-0001-8832-4488
Saunders, Nicholas0000-0003-2657-3889
Additional Information:We thank the Palomar Observatory telescope operators and support astronomers for their support of this work. We additionally thank Adrian Barker, Konstantin Batygin, Dave Charbonneau, Jim Fuller, Mercedes López-Morales, Morgan MacLeod, and Sam Yee for insightful comments and discussions. This paper is based on data collected by the TESS mission. Funding for the TESS mission is provided by NASA’s Science Mission Directorate. We acknowledge the use of public TESS data from pipelines at the TESS Science Office and at the TESS Science Processing Operations Center. This research has made use of the Exoplanet Follow-up Observation Program website, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. D.H. acknowledges support from the Alfred P. Sloan Foundation and the National Aeronautics and Space Administration (80NSSC19K0597, 80NSSC21K0652).
Group:Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20230124-11595100.4
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118913
Deposited By: Research Services Depository
Deposited On:17 Feb 2023 03:10
Last Modified:17 Feb 2023 03:10

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