Water condensation zones around main sequence stars
Year: 2023
Type: article
Abstract: Understanding the set of conditions that allow rocky planets to have liquid water on their surface, in the form of lakes, seas, or oceans, is a major scientific step in determining the fraction of planets potentially suitable for the emergence and development of life as we know it on Earth. This effort is also necessary to define and refine what is known as the habitable zone (HZ) in order to guide the search for exoplanets likely to harbor remotely detectable life forms. To date, most numerical climate studies on this topic have focused on the conditions necessary to maintain oceans, but not to form them in the first place. Here we use the three-dimensional Generic Planetary Climate Model, historically known as the LMD generic global climate model, to simulate water-dominated planetary atmospheres around different types of main sequence stars. The simulations are designed to reproduce the conditions of early ocean formation on rocky planets due to the condensation of the primordial water reservoir at the end of the magma ocean phase. We show that the incoming stellar radiation (ISR) required to form oceans by condensation is always drastically lower than that required to vaporize oceans. We introduce a water condensation limit, which lies at significantly lower ISR than the inner edge of the HZ calculated with three-dimensional numerical climate simulations. This difference is due to a behavior change of water clouds, from low-altitude dayside convective clouds to high-altitude nightside stratospheric clouds. Finally, we calculated the transit spectra, emission spectra, and thermal phase curves of TRAPPIST-1b, c, and d with H2O-rich atmospheres, and compared them to CO2 atmospheres and bare rock simulations. We show using these observables that JWST has the capability to probe steam atmospheres on low-mass planets, and could possibly test the existence of nightside water clouds.
Source: Astronomy and Astrophysics
Institutions: University of Geneva, Centre National de la Recherche Scientifique, École Polytechnique, Université Paris Sciences et Lettres, Sorbonne Université, Laboratoire de Météorologie Dynamique, Laboratoire d'Astrophysique de Bordeaux, Institut Polytechnique de Paris, Goddard Space Flight Center, American University, Institut d'Astrophysique de Paris, Université Paris Cité, Observatoire de Paris, Laboratoire d’études spatiales et d’instrumentation en astrophysique, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Université Paris-Saclay, Astrophysique, Instrumentation et Modélisation, University of Liège, Université Pierre-et-Marie-Curie
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,623
Funders: National Science Foundation, National Aeronautics and Space Administration, Gruber Foundation, European Commission, Agence Nationale de la Recherche, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Belgian Federal Science Policy Office, Centre National d’Etudes Spatiales, Grand Équipement National De Calcul Intensif, Sorbonne Université, Goddard Space Flight Center, Planetary Science Division, H2020 European Research Council
Awards: G1887303454, Simulations and Observations of Uranus and Neptune atmospheric Dynamics, G434337789, Exploring Shortcuts for the Characterization of the Atmospheres of Planets similar to Earth, WHat next? an Integrated PLanetary Atmosphere Simulator: from Habitable worlds to Hot jupiters, G8478695503
OpenAlex ID: W4386991985