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Abundance and icy grain surface chemistry of O2 in comet 67P/Churyumov-Gerasimenko: through ROSINA/DFMS measurements and molecular and kinetic modelling

par Gibbons, Andrew
Président du jury Prévost, Martine
Promoteur Vaeck, Nathalie
Co-Promoteur De Keyser, Johan
Publication Non publié, 2019-09-13

Thèse de doctorat

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Résumé :

This multidisciplinary work revolves around cometary science, molecular and kinetic modelling, mass spectrometry and astrochemistry. First of all, the abundance of O2 and its variability in the atmosphere (or coma) of comet 67P/Churyumov-Gerasimenko are studied by analysing the mass spectra measured by ROSINA/DFMS, a high mass resolution mass spectrometer flown aboard the ESA Rosetta mission. As a second step, the interaction between O2 and an amorphous water ice surface is studied at the molecular level in order to extract the binding properties of O2 to the icy surfaces of the dust grains present in the coma of 67P/C-G. In a final chapter, the chemistry occurring in the coma is explored using a kinetic model of 67P/C-G, including a term describing the release of O2 from the surfaces of icy grains. These three research axes are combined to draw new conclusions on the abundance of cometary O2 and its chemistry in the coma of 67P/C-G, including its variability and its release from icy grains.