Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets

Terrestrial planets in the habitable zone (HZ) of Sun-like stars are priority targets for detection and observation by the next generation of space telescopes. Earth's long-term habitability may have been tied to the geological carbon cycle, a process critically facilitated by plate tectonics....

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Main Authors: Antonin Affholder, Stéphane Mazevet, Boris Sauterey, Dániel Apai, Régis Ferrière
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astronomical Journal
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Online Access:https://doi.org/10.3847/1538-3881/ada384
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author Antonin Affholder
Stéphane Mazevet
Boris Sauterey
Dániel Apai
Régis Ferrière
author_facet Antonin Affholder
Stéphane Mazevet
Boris Sauterey
Dániel Apai
Régis Ferrière
author_sort Antonin Affholder
collection DOAJ
description Terrestrial planets in the habitable zone (HZ) of Sun-like stars are priority targets for detection and observation by the next generation of space telescopes. Earth's long-term habitability may have been tied to the geological carbon cycle, a process critically facilitated by plate tectonics. In the modern Earth, plate motion corresponds to a mantle convection regime called mobile lid. The alternate, stagnant-lid regime is found on Mars and Venus, which may have lacked strong enough weathering feedback to sustain surface liquid water over geological timescales if initially present. Constraining observational strategies able to infer the most common regime in terrestrial exoplanets requires quantitative predictions of the atmospheric composition of planets in either regime. We use end-member models of volcanic outgassing and crust weathering for the stagnant- and mobile-lid convection regimes, which we couple to models of atmospheric chemistry and climate and ocean chemistry to simulate the atmospheric evolution of these worlds in the HZ. In our simulations under the two alternate regimes, we find that the fraction of planets possessing climates consistent with surface liquid water is virtually the same. Despite this unexpected similarity, we predict that a mission capable of detecting atmospheric CO _2 abundance above 0.1 bar in 25 terrestrial exoplanets is extremely likely (≥95% of samples) to infer the dominant interior convection regime in that sample with strong evidence (10:1 odds). This offers guidance for the specifications of the Habitable Worlds Observatory NASA concept mission and other future missions capable of probing samples of habitable exoplanets.
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spelling doaj-art-12abd3f80d99438f935f90d0c7fadcdb2025-02-05T09:26:39ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169312510.3847/1538-3881/ada384Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial ExoplanetsAntonin Affholder0https://orcid.org/0000-0003-3481-0952Stéphane Mazevet1https://orcid.org/0000-0003-3557-6256Boris Sauterey2https://orcid.org/0000-0001-6164-756XDániel Apai3https://orcid.org/0000-0003-3714-5855Régis Ferrière4https://orcid.org/0000-0002-5806-5566Department of Ecology and Evolutionary Biology, University of Arizona , Tucson, AZ, USA ; antoaffh@gmail.comObservatoire de la Côte d’Azur, Université Côte d’Azur , Nice, FranceDépartement de Géosciences, ENS , PSL, Paris, FranceSteward Observatory, University of Arizona , Tucson, AZ, USA; Lunar and Planetary Laboratory, University of Arizona , Tucson, AZ, USADepartment of Ecology and Evolutionary Biology, University of Arizona , Tucson, AZ, USA ; antoaffh@gmail.com; Institut de Biologie de l’École Normale Supérieure , ENS, PSL, Paris, France; International Research Laboratory for Interdisciplinary Global Environmental Studies (iGLOBES), CNRS, ENS, PSL, University of Arizona , Tucson, AZ, USATerrestrial planets in the habitable zone (HZ) of Sun-like stars are priority targets for detection and observation by the next generation of space telescopes. Earth's long-term habitability may have been tied to the geological carbon cycle, a process critically facilitated by plate tectonics. In the modern Earth, plate motion corresponds to a mantle convection regime called mobile lid. The alternate, stagnant-lid regime is found on Mars and Venus, which may have lacked strong enough weathering feedback to sustain surface liquid water over geological timescales if initially present. Constraining observational strategies able to infer the most common regime in terrestrial exoplanets requires quantitative predictions of the atmospheric composition of planets in either regime. We use end-member models of volcanic outgassing and crust weathering for the stagnant- and mobile-lid convection regimes, which we couple to models of atmospheric chemistry and climate and ocean chemistry to simulate the atmospheric evolution of these worlds in the HZ. In our simulations under the two alternate regimes, we find that the fraction of planets possessing climates consistent with surface liquid water is virtually the same. Despite this unexpected similarity, we predict that a mission capable of detecting atmospheric CO _2 abundance above 0.1 bar in 25 terrestrial exoplanets is extremely likely (≥95% of samples) to infer the dominant interior convection regime in that sample with strong evidence (10:1 odds). This offers guidance for the specifications of the Habitable Worlds Observatory NASA concept mission and other future missions capable of probing samples of habitable exoplanets.https://doi.org/10.3847/1538-3881/ada384ExoplanetsExtrasolar rocky planetsAstrobiologyPlanetary interiorExoplanet atmospheresExoplanet atmospheric evolution
spellingShingle Antonin Affholder
Stéphane Mazevet
Boris Sauterey
Dániel Apai
Régis Ferrière
Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
The Astronomical Journal
Exoplanets
Extrasolar rocky planets
Astrobiology
Planetary interior
Exoplanet atmospheres
Exoplanet atmospheric evolution
title Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
title_full Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
title_fullStr Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
title_full_unstemmed Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
title_short Interior Convection Regime, Host Star Luminosity, and Predicted Atmospheric CO2 Abundance in Terrestrial Exoplanets
title_sort interior convection regime host star luminosity and predicted atmospheric co2 abundance in terrestrial exoplanets
topic Exoplanets
Extrasolar rocky planets
Astrobiology
Planetary interior
Exoplanet atmospheres
Exoplanet atmospheric evolution
url https://doi.org/10.3847/1538-3881/ada384
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