With the rapidly growing number of extrasolar planets detected, we have firmly stepped into the era of detailed characterization. Diverse types of exoplanets such as gas giants on close-in orbits ... Show moreWith the rapidly growing number of extrasolar planets detected, we have firmly stepped into the era of detailed characterization. Diverse types of exoplanets such as gas giants on close-in orbits (hot Jupiters) and young massive giants on wide orbits (super Jupiters), with no analogs in the Solar System, pose challenges but also opportunities to our understanding of planet formation and evolution. Exoplanet atmospheres with imprints from their history open an important avenue to retrace the origin and evolution of planets. With high-dispersion spectroscopy, we can resolve atomic and molecular spectral features into unique forests of lines that serve as the fingerprints for identifying different species in planetary atmospheres. In this dissertation, I utilize this technique to explore atmospheric compositions, thermal structures, and dynamics of exoplanet atmospheres. I have discovered minor isotopologues in emission spectra of an exoplanet and a brown dwarf for the first time, pioneering the use of carbon isotopic ratios as potential tracers of planet formation. I have investigated the trend of atomic absorption strengths in a sample of ultra-hot Jupiters, which enables disentangling different dynamic regimes of highly-irradiated exoplanets. These works form the foundation to link spectroscopic observations to planet formation and evolution processes. Show less
Mulders, G.D.; Drążkowska, J.; Marel, N. van der; Ciesla, F.J.; Pascucci, I. 2021
This thesis addresses the chemical processes that determine the compositions of giant planet atmospheres. Connecting the observed composition of exoplanets to their formation sites often involves... Show moreThis thesis addresses the chemical processes that determine the compositions of giant planet atmospheres. Connecting the observed composition of exoplanets to their formation sites often involves comparing the observed planetary atmospheric carbon-to-oxygen (C/O) ratio to a disk midplane model with a fixed chemical composition. In this scenario chemistry during the planet formation era is not considered, and the C/O ratios of gas and ice in disk midplane are simply defined by volatile icelines in a midplane of fixed chemical composition. However, kinetic chemical evolution during the lifetime of the gaseous disk can change the relative abundances of volatile species, thus altering the C/O ratios of planetary building blocks. In my chemical evolution models I utilize a large network of gas-phase, grain-surface and gas-grain interaction reactions, thus providing a comprehensive treatment of chemistry. In my talk I will show how chemical evolution can modify disk miplane chemistry and how this affects the C/O ratio of giant planet-forming material. I will argue that midplane chemical evolution needs to be addressed when predicting the chemical makeup of planets and their atmospheres. And as an extra, I will propose that chemical evolution can help constrain the formation histories of comets. Show less
The different chapters cover studies in which the physical structures of the gas such as temperature, densities and movements of the gas are estimated. In addition chemical characteristics of the... Show moreThe different chapters cover studies in which the physical structures of the gas such as temperature, densities and movements of the gas are estimated. In addition chemical characteristics of the gas such as different molecular abundances and their spatial distribution are defined. This information is discussed in the context of how the chemical evolution of the gas in the planet-forming region progress and how this affects which type of planets that can form there. The results are mainly based on infrared observations and radiative transfer disk models. Show less
