Year: 2026
Type: preprint
Abstract: Super-Earth exoplanets are among the most abundant planets known, yet their bulk densities leave the interior state degenerate. The static structure models used to interpret them, and the interior retrievals built on them, typically describe the cold, solidified end state of an evolution that begins hot and molten. During this magma ocean stage the interior, the outgassed atmosphere, and the surface co-evolve and set the long-term climate and geophysics of super-Earths. We develop and validate a fully coupled model for the structural and thermal evolution of super-Earth exoplanets within the PROTEUS framework, including new and upgraded models of the interior structure, mantle energetics, and volatile outgassing. In volatile-poor super-Earths of 1 to 10 Earth masses, the silicate interior contracts by about 10 % of its molten radius through cooling and crystallisation, nearly independent of planet mass and driven by the thinning silicate shell alone. The solidified radius is set by planetary mass and core fraction, insensitive to the host star, irradiation, and initial thermal state. In contrast, volatile-rich super-Earths at and above about 5 Earth masses may not solidify: their thick outgassed atmospheres throttle the surface heat loss until the interior settles into a deep magma ocean, keeping the planet inflated and limiting the contraction to about half its volatile-poor value. Mantle contraction alone thus shapes the low-mass exoplanet transit population, motivating joint interpretation of atmospheric and geophysical signatures in upcoming exoplanet surveys.
Source: arXiv (Cornell University)
Authors: Lichtenberg, Tim, Attia, Mara, Nicholls, Harrison, Sastre, Mariana, Bower, Dan J., Stuitje, Karen, Pascal, Flavia C., Soucasse, Laurent, Apai, Daniel, Bos, Patrick, Calder, Robb, Cesario, Lorenzo, Dang, Lisa, Decocq, Emeline, van Dijk, Marijn, Farhat, Mohammad, Hakim, Kaustubh, Kimura, Tadahiro, Kisvárdai, Imre, Krijt, Sebastiaan, Miguel, Yamila, Panagiotou, Ioannis, Postolec, Emma, Schlecker, Martin, Seager, Sara, Shahar, Anat, Shorttle, Oliver, Sossi, Paolo A., van Westrenen, Wim
Institutions: University of Groningen, University of Cambridge, ETH Zurich, Netherlands eScience Center, IMEC, University of Arizona, University of Waterloo, University of California, Berkeley, Royal Observatory of Belgium, KU Leuven, UTokyo Organization for Planetary and Space Science, The University of Tokyo, University of Exeter, Leiden University, Leiden Observatory, Space Research Organisation Netherlands, European Southern Observatory, Massachusetts Institute of Technology, Carnegie Institution for Science, Earth and Planets Laboratory, Vrije Universiteit Amsterdam
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Aeronautics and Space Administration, Alfred P. Sloan Foundation, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Rijksuniversiteit Groningen, Belgian Federal Science Policy Office, Fonds Wetenschappelijk Onderzoek, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, HORIZON EUROPE Framework Programme, Science and Technology Facilities Council, Staatssekretariat für Bildung, Forschung und Innovation
Awards: G1637277234, G3052982938, PRELIFE - Pathways, Reactions, and Environments leading to LIFE: An interdisciplinary approach., STFC Cambridge Astronomy 2023 DTP, New gas solubility measurements in magma to model C/O in sub-Neptune atmospheres, G6686480456, Charting the Evolution of Alien Worlds: Integrating Interior, Atmospheric, and Orbital Processes, Distinguishing oceans of water from magma on sub-Neptunes, Non-variant antigens of trypanosomes as potential target for vaccination
OpenAlex ID: W7214020688