Egger, Jo Ann (2025). Uncovering the Interiors of Super-Earths and Sub-Neptunes. Insights from the CHEOPS Mission. (Thesis). Universität Bern, Bern
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Abstract
The observed exoplanet population exhibits a remarkable diversity of planetary masses and radii, with many of the discovered planets not having analogues in the solar system. This dissertation explores how precise exoplanet observations can be linked with theoretical models to investigate the interiors of super-Earths and sub-Neptunes, with a special focus on the planets observed by ESA’s CHEOPS mission. This is of particular interest since the compositions of these planets were shaped by their formation and evolution pathways and can therefore provide valuable constraints on planet formation theory. A key component of this dissertation is the development of the plaNETic code, an open-source, neural network-based framework that enables a fast and reliable inference of exoplanetary internal structures. Over the course of my PhD, I applied this framework to around 60 observed exoplanets, contributing to more than 20 observational publications as a co-author. On the observational side, I was part of the CHEOPS science team and managed multiple observational Guaranteed Time Observation (GTO) programmes, as well as obtaining observing time on HARPS and ESPRESSO as PI. In this way, I contributed to a precise and accurate characterisation of the planetary radii and masses of multiple super-Earths and sub-Neptunes. My first publication on the planetary system orbiting the evolved K dwarf TOI-469 presents 9.6 days of new CHEOPS data, significantly refining the planetary radii of all three planets and performing an extensive theoretical analysis of the planetary system, including a new formation track analysis utilising a synthetic population of the Bern model of planet formation and evolution. Also the plaNETic framework was introduced in this paper. My second publication introduced the concept and first observational data of my CHEOPS GTO programme Hot Water Worlds, aimed at identifying new exoplanets that lie in special triangular regions in the mass–radius space, where they can only exist if they contain at least some volatiles heavier than H/He. By bridging the gap between theory and observations, my research demonstrates how we can deepen our understanding of exoplanetary systems through a combination of precise observational characterisation and theoretical modelling. As current and future telescopes like CHEOPS, JWST, PLATO, Ariel, and the ELT continue to push the boundaries of exoplanet characterisation, linking their observations with theoretical models will become more important than ever in the quest to understand the nature of exoplanets and their potential for harbouring life.
| Item Type: | Thesis |
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| Dissertation Type: | Cumulative |
| Date of Defense: | 23 May 2025 |
| Subjects: | 500 Science > 520 Astronomy 500 Science > 530 Physics |
| Institute / Center: | 08 Faculty of Science > Physics Institute |
| Depositing User: | Hammer Igor |
| Date Deposited: | 15 Jul 2025 16:17 |
| Last Modified: | 15 Jul 2025 17:03 |
| URI: | https://boristheses.unibe.ch/id/eprint/6380 |
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