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Self-limited tidal heating and prolonged magma oceans in the L 98-59 system

Abstract:
Rocky exoplanets accessible to characterization often lie on close-in orbits where tidal heating within their interiors is significant, with the L 98-59 planetary system being a prime example. As a long-term energy source for ongoing mantle melting and outgassing, tidal heating has been considered as a way to replenish lost atmospheres on rocky planets around active M-dwarfs. We simulate the early evolution of L 98-59 b, c, and d using a time-evolved interior-atmosphere modelling framework, with a self-consistent implementation of tidal heating and redox-controlled outgassing. Emerging from our calculations is a novel self-limiting mechanism between radiative cooling, tidal heating, and mantle rheology, which we term the ‘radiation-tide-rheology feedback’. Our coupled modelling yields self-limiting tidal heating estimates that are up to two orders of magnitude lower than previous calculations, and yet are still large enough to enable the extension of primordial magma oceans to Gyr time-scales. Comparisons with a semi-analytic model demonstrate that this negative feedback is a robust mechanism which can probe a given planet’s initial conditions, atmospheric composition, and interior structure. The orbit and instellation of the sub-Venus L 98-59 b likely place it in a regime where tidal heating has kept the planet molten up to the present day, even if it were to have lost its atmosphere. For c and d, a long-lived magma ocean can be induced by tides only with additional atmospheric regulation of energy transport.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1093/mnras/staf1167

Authors


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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Physics - Central
Role:
Author
ORCID:
0000-0002-8368-4641
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Physics - Central
Role:
Author
ORCID:
0000-0003-1521-5461
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Earth Sciences
Sub department:
Earth Sciences
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Physics - Central
Role:
Author
More by this author
Role:
Author
ORCID:
0000-0002-3286-7683


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Funder identifier:
https://ror.org/057g20z61
More from this funder
Funder identifier:
https://ror.org/00rbjv475
More from this funder
Funder identifier:
https://ror.org/052csg198


Publisher:
Oxford University Press
Journal:
Monthly Notices of the Royal Astronomical Society More from this journal
Volume:
541
Issue:
3
Pages:
2566-2584
Publication date:
2025-07-16
Acceptance date:
2025-09-09
DOI:
EISSN:
1365-2966
ISSN:
0035-8711


Language:
English
Keywords:
Source identifiers:
3144482
Deposit date:
2025-07-24
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