Hot Jupiters Are Asynchronous Rotators

Hot Jupiters are typically assumed to be synchronously rotating, from tidal locking. Their thermally driven atmospheric winds experience Lorentz drag on the planetary magnetic field anchored at depth. We find that the magnetic torque does not integrate to zero over the entire atmosphere. The resulti...

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Main Authors: Marek Wazny, Kristen Menou
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
Subjects:
Online Access:https://doi.org/10.3847/2041-8213/ada954
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author Marek Wazny
Kristen Menou
author_facet Marek Wazny
Kristen Menou
author_sort Marek Wazny
collection DOAJ
description Hot Jupiters are typically assumed to be synchronously rotating, from tidal locking. Their thermally driven atmospheric winds experience Lorentz drag on the planetary magnetic field anchored at depth. We find that the magnetic torque does not integrate to zero over the entire atmosphere. The resulting angular momentum feedback on the bulk interior can thus drive the planet away from synchronous rotation. Using a toy tidal–ohmic model and atmospheric general circulation model outputs for HD189733b, HD209458b, and Kepler7b, we establish that off-synchronous rotation can be substantial at tidal–ohmic equilibrium for sufficiently hot and/or magnetized hot Jupiters. Potential consequences of asynchronous rotation for hot Jupiter phenomenology motivate follow-up work on the tidal–ohmic scenario with approaches that go beyond our toy model.
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spelling doaj-art-c37fc274174f4af78d43dde5d5ef4df02025-08-20T02:25:47ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019792L3110.3847/2041-8213/ada954Hot Jupiters Are Asynchronous RotatorsMarek Wazny0https://orcid.org/0009-0001-7562-1798Kristen Menou1David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada; Department of Physics, University of Toronto , 60 St. George Street, Toronto, ON M5S 1A7, CanadaDavid A. Dunlap Department of Astronomy & Astrophysics, University of Toronto , 50 St. George Street, Toronto, ON M5S 3H4, Canada; Department of Physics, University of Toronto , 60 St. George Street, Toronto, ON M5S 1A7, Canada; Physics & Astrophysics Group, Department of Physical & Environmental Sciences, University of Toronto Scarborough , 1265 Military Trail, Toronto, ON M1C 1A4, Canada; Observatoire de la Cote d’Azur , TOP team, Laboratoire Lagrange - CNRS, Nice, FranceHot Jupiters are typically assumed to be synchronously rotating, from tidal locking. Their thermally driven atmospheric winds experience Lorentz drag on the planetary magnetic field anchored at depth. We find that the magnetic torque does not integrate to zero over the entire atmosphere. The resulting angular momentum feedback on the bulk interior can thus drive the planet away from synchronous rotation. Using a toy tidal–ohmic model and atmospheric general circulation model outputs for HD189733b, HD209458b, and Kepler7b, we establish that off-synchronous rotation can be substantial at tidal–ohmic equilibrium for sufficiently hot and/or magnetized hot Jupiters. Potential consequences of asynchronous rotation for hot Jupiter phenomenology motivate follow-up work on the tidal–ohmic scenario with approaches that go beyond our toy model.https://doi.org/10.3847/2041-8213/ada954Hot JupitersMagnetic fieldsTidal disruption
spellingShingle Marek Wazny
Kristen Menou
Hot Jupiters Are Asynchronous Rotators
The Astrophysical Journal Letters
Hot Jupiters
Magnetic fields
Tidal disruption
title Hot Jupiters Are Asynchronous Rotators
title_full Hot Jupiters Are Asynchronous Rotators
title_fullStr Hot Jupiters Are Asynchronous Rotators
title_full_unstemmed Hot Jupiters Are Asynchronous Rotators
title_short Hot Jupiters Are Asynchronous Rotators
title_sort hot jupiters are asynchronous rotators
topic Hot Jupiters
Magnetic fields
Tidal disruption
url https://doi.org/10.3847/2041-8213/ada954
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