Chemistry of rocky exoplanet atmospheres

Drant, Thomas (2024): Chemistry of rocky exoplanet atmospheres: towards a better understanding of gas and haze observables in the era of JWST. Dissertation, LMU München: Fakultät für Physik

Abstract

In December 2021, the James Webb Space Telescope (JWST) was launched marking the beginning of an active decade of research focusing on the characterization of exoplanet atmospheres. The first observations of JWST already suggest the detection of simple species (CO2, CH4 and H2O) and aerosols in rocky exoplanet atmospheres. These observables hold crucial information on the chemical processes occurring in the atmosphere. Their detection and the quantification of their abundances can help constrain important properties of the atmosphere, its origin and the conditions found at the surface. In this thesis, I focus on three types of observables providing different information on rocky exoplanet atmospheres: gaseous photochemical products in habitable worlds, photochemical hazes with a focus on their intrinsic optical properties, and simple volatiles tracing properties of the rocky interior in warm and non-habitable environments. Using laboratory experiments and theoretical modelling, I studied these different observables to better understand the information they can provide and to improve future interpretation of JWST data. For photochemical products in habitable worlds, I assessed the formation of water vapor by photochemistry in the upper atmosphere, above the cloud cover, and its correlation to the presence of volcanic H2. For warmer rocky exoplanet atmospheres, I used modelling combining geochemical outgassing, atmospheric chemistry and radiative transfer to assess the correlation between the observed relative molecular abundances of volatiles in the atmosphere (e.g. CO2/CO) and the interior redox state of the planet. To understand the extinction caused by photochemical hazes in exoplanet atmospheres, I focused on the influence of the particle’s composition by deriving the refractive indices of laboratory analogues. I assessed the impact of the optical technique, gas composition and experimental conditions (irradiation, temperature, residence time of the gas) on these refractive indices.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: exoplanet atmospheres, chemistry, aerosols, atmospheric modelling, laboratory experiments
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 530 Physik
• Fakultäten: Fakultät für Physik
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 1. Oktober 2024
• 1. Bericht­erstatter:in: Heng, Kevin