Interior redox state effects on the stability of secondary atmospheres and observational manifestations: LP 791-18 d as a case study for outgassing rocky exoplanets

Fuente: arXiv
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Autori principali: Gkouvelis, Leonardos, Pozuelos, Francisco J., Drant, Thomas, Farhat, Mohammad, Tian, Meng, Akın, Can
Natura: Preprint
Pubblicazione: 2025
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author Gkouvelis, Leonardos
Pozuelos, Francisco J.
Drant, Thomas
Farhat, Mohammad
Tian, Meng
Akın, Can
author_facet Gkouvelis, Leonardos
Pozuelos, Francisco J.
Drant, Thomas
Farhat, Mohammad
Tian, Meng
Akın, Can
contents Recent advances in space and ground-based facilities now enable atmospheric characterization of a selected sample of rocky exoplanets. These atmospheres offer key insights into planetary formation and evolution, but their interpretation requires models that couple atmospheric processes with both the planetary interior and the surrounding space environment. This work focuses on the Earth-size planet LP791 18d, which is estimated to receive continuous tidal heating due to the orbital configuration of the system; thus, it is expected to exhibit volcanic activity. We estimate the mantle temperature of 1680-1880 K. Our results show that the atmospheric mean molecular weight gradient is controlled by oxygen fugacity rather than bulk metallicity. Furthermore, we use the atmospheric steady-state solutions produced from the interior redox state versus surface pressure parameter space and explore their atmospheric stability. We find that stability is achieved only in highly oxidized scenarios while reduced interior states fall into the hydrodynamic escape regime with mass loss rates on the order of 10^5-10^8 kg/s. We argue that scenarios with reduced interior states are likely to have exhausted their volatile budget during the planets lifetime. Furthermore, we predict the atmospheric footprint of the planets interior based on its oxidation state and assess its detectability using current or forthcoming tools to constrain the internal and atmospheric composition. We show that the degeneracy between bare rock surfaces and thick atmospheres can be resolved by using three photometric bands to construct a color-color diagram that accounts for potential effects from photochemical hazes and clouds. Our modeling approach connects interior and atmospheric processes, providing a basis to explore volatile evolution and potential habitability.
format Preprint
id arxiv_https___arxiv_org_abs_2506_02188
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Interior redox state effects on the stability of secondary atmospheres and observational manifestations: LP 791-18 d as a case study for outgassing rocky exoplanets
Gkouvelis, Leonardos
Pozuelos, Francisco J.
Drant, Thomas
Farhat, Mohammad
Tian, Meng
Akın, Can
Earth and Planetary Astrophysics
Recent advances in space and ground-based facilities now enable atmospheric characterization of a selected sample of rocky exoplanets. These atmospheres offer key insights into planetary formation and evolution, but their interpretation requires models that couple atmospheric processes with both the planetary interior and the surrounding space environment. This work focuses on the Earth-size planet LP791 18d, which is estimated to receive continuous tidal heating due to the orbital configuration of the system; thus, it is expected to exhibit volcanic activity. We estimate the mantle temperature of 1680-1880 K. Our results show that the atmospheric mean molecular weight gradient is controlled by oxygen fugacity rather than bulk metallicity. Furthermore, we use the atmospheric steady-state solutions produced from the interior redox state versus surface pressure parameter space and explore their atmospheric stability. We find that stability is achieved only in highly oxidized scenarios while reduced interior states fall into the hydrodynamic escape regime with mass loss rates on the order of 10^5-10^8 kg/s. We argue that scenarios with reduced interior states are likely to have exhausted their volatile budget during the planets lifetime. Furthermore, we predict the atmospheric footprint of the planets interior based on its oxidation state and assess its detectability using current or forthcoming tools to constrain the internal and atmospheric composition. We show that the degeneracy between bare rock surfaces and thick atmospheres can be resolved by using three photometric bands to construct a color-color diagram that accounts for potential effects from photochemical hazes and clouds. Our modeling approach connects interior and atmospheric processes, providing a basis to explore volatile evolution and potential habitability.
title Interior redox state effects on the stability of secondary atmospheres and observational manifestations: LP 791-18 d as a case study for outgassing rocky exoplanets
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2506.02188