Climate Patterns of Spin-Orbit Resonant Exoplanets Around Low-Mass Stars

Di Paolo, Maria, Stevens, David P. and Joshi, Manoj (2026) Climate Patterns of Spin-Orbit Resonant Exoplanets Around Low-Mass Stars. The Astrophysical Journal. ISSN 0004-637X (In Press)

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Abstract

M dwarfs are the most promising candidates for finding habitable worlds through atmospheric characterization. Planets in the habitable zone of low-mass stars experience intense tidal forcings and often become tidally locked. Despite the majority of research being centered on the climate dynamics of synchronously rotating planets in this scenario, synchronous rotation is not an inevitable outcome of tidal locking. Several different circumstances can result in an asynchronous rotation, and in some instances can lead to spin-orbit resonances (SORs). We explore the climates of two different spin-orbit resonant scenarios with a coupled atmosphere-ocean general circulation climate model. Given the crucial role played by the oceans in shaping planetary climate, we adopt two different ocean tidal forcing parameterizations for each SOR scenario. Each of these cases are simulated with both a dynamic ocean and a thermodynamic ocean. Our findings reveal striking differences between the analyzed resonant case and the commonly studied synchronous rotation case. Periodic climate patterns are observed, with climatic features such as clouds and rainfall exhibiting a 60$^\circ$ longitudinal shift relative to the substellar point. The evolution of quantities such as thermal emission and reflected light during a stellar period is noteworthy from the observational point of view, showing appreciable differences compared to the synchronous rotation scenario.

Item Type:	Article
Additional Information:	Code and Data Availability: The FORTE2.0 Blaker et al. (2021) code, compilation instructions and example run scripts, together with all necessary ancillary files, are accessible at doi.org/10.5281/zenodo.4108373. The data that support the findings of this study are accessible at doi.org/10.5281/zenodo.17885048.
Uncontrolled Keywords:	atmospheric circulation (112) — atmospheric dynamics,exoplanets,spin-orbit resonances,ocean tides,habitable planets,m stars,planetary climates,ocean-atmosphere interactions,astrobiology,exoplanet atmospheres,planetary atmospheres
Faculty \ School:	Faculty of Science > School of Engineering, Mathematics and Physics University of East Anglia Research Groups/Centres > Theme - ClimateUEA Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Fluids & Structures Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Climatic Research Unit University of East Anglia Schools > Faculty of Science > Tyndall Centre for Climate Change Research Faculty of Science > Research Centres > Tyndall Centre for Climate Change Research
Depositing User:	LivePure Connector
Date Deposited:	28 May 2026 14:09
Last Modified:	28 May 2026 14:09
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103193
DOI:	issn:0004-637X

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