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Exploring Titan’s Atmosphere Composition and Temporal Evolution using High-Resolution Spectroscopy, and its Interaction with the Surface using Atomistic Molecular Dynamics Simulations

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Resumo:The atmosphere of Titan is a unique natural laboratory for the study of atmospheric evolution and photochemistry akin to that of the primitive Earth, with a wide array of complex molecules discovered through infrared and sub-mm spectroscopy. Experimental simulations have suggested the synthesis of organic molecules under the conditions of Titan’s atmosphere. In this work, I analysed very high-resolution visible VLT/UVES spectra of Titan and developed a new line characterisation method that retrieved an empirical high resolution linelist of methane (CH4) with 97 new absorption lines between 5250Å and 6180Å, for 4 CH4 visible bands for which no similar linelists are yet available. Furthermore, I searched for the predicted, but previously undetected carbon trimer, C3, on the atmosphere of Titan, at its 4051Å band on VLT/UVES spectra. The results are consistent with the presence of C3 at the upper atmosphere of Titan, with a column density of 1013 cm−2 . This first tentative detection of C3 in Titan may provide much needed constraints to models of its upper atmosphere photochemistry. I have also run molecular dynamics simulations of amino acid films in Titan, aiming to computationally replicate laboratory experiments and measure intermolecular interactions between amino acid molecules. This study of Titan’s atmosphere with very high-resolution visible spectroscopy presents a unique opportunity to observe a small planetary target with CH4 on its atmosphere, from which CH4 optical proprieties can be studied. It also showcases the use of a close planetary target to test new methods for chemical retrieval of minor atmospheric compounds, in preparation for upcoming studies of cold terrestrial exoplanet atmospheres. Molecular dynamics simulations of organic molecules performed during this work are complementary to laboratory and future in situ studies of organic molecules in extraterrestrial environments, paving the way to assess the potential for habitability of icy moons.
Autores principais:Silva, Rafael Duarte Rianço Gomes da
Assunto:Atmosferas planetárias Titã Moléculas orgânicas Espectroscopia de alta resolução Simulações de dinâmica molecular Teses de mestrado - 2024
Ano:2024
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso aberto
Instituição associada:Universidade de Lisboa
Idioma:inglês
Origem:Repositório da Universidade de Lisboa

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