Anne Boucher’s doctoral project focused on studying the atmosphere of gas giant exoplanets that are very close to their star, i.e. hot Jupiters and hot sub-Saturns. To study their atmosphere, she used the method of transmission spectroscopy using high-resolution data from the SPIRou instrument, the SpectroPolarimètre InfraRouge. This method allows us to know more about the chemical composition, the dynamics, and the temperature structure of their atmosphere, and gives us a lot of information on how the planets formed and evolved.
The data analysis and extraction codes were built and tested on data from one of the most studied exoplanets, the hot Jupiter HD 189733 b. The method was validated by the detection of water vapour, probably strong winds and very few clouds on this planet, which are all results consistent with those of the literature.
Next, Anne studied the very puffy exoplanet WASP-127 b, a hot sub-Saturn orbiting a very old star. The first joint analysis that combines high- and low-resolution data in transit was done with WASP-127b, and yielded much more precise constraints on atmospheric parameters like chemical composition and cloud altitude. This study also made it possible to differentiate between two possible composition scenarios that had been presented in a previous study, and showed that WASP-127b is not in chemical equilibrium and has an atypical formation history.
Thanks to this work, expertise with the method of high-resolution transit spectroscopy in the near infrared at the University of Montreal has been developed, in particular with SPIRou, thus making it possible to explore the atmosphere of hot Jupiters and sub-Saturns. Joint analysis is proving to be a very powerful tool for studying the atmospheres of exoplanets and will be even more so with the revolutionary capabilities of the James Webb Space Telescope.
Anne continues her high-resolution transit spectroscopy work, still with SPIRou, but for the study of an ultra hot Jupiter, which has a much more extreme atmosphere than the two previous ones. She will thus be able to characterize its atmosphere and discover its mysteries.