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Antoine Darveau-Bernier, an iREx student at the Université de Montréal, submitted his thesis in the fall of 2022. Here he summarizes the research projects he carried out as part of his Ph.D. Studying the atmospheres of the hottest giant exoplanets, from Earth and from space My PhD aimed at developing data analysis techniques for the study of exoplanet atmospheres. I was then able to apply one of these methods to observe the second hottest exoplanet known to date, WASP-33 b. To do this, we used the SPIRou instrument located on the Canada-France-Hawaii telescope. This planet, similar in size and mass to Jupiter, is so close to its star that it only takes 29 hours to orbit it! This proximity has the effect of causing WASP-33 b to always point the same side to its star, a bit like the Moon and Earth. This “dayside” is constantly irradiated by its star and can thus reach extremely high temperatures (up to 3400°C!), approaching those of cooler stars. Our analysis allowed us to measure for the first time the abundance of carbon monoxide present in this planet’s atmosphere, in addition to measuring the temperature present at different altitudes. Artist’s rendering of the James Webb Space Telescope, which Antoine worked on during his Ph.D. Credit. NASA GSFC/CIL/Adriana Manrique Gutierrez. To achieve this, we had to apply a new method to distinguish the light emitted from the atmosphere of WASP-33 b, and that is buried in the signal of its star. By decomposing this light according to its different colors (wavelengths), it is possible to detect the signature of many molecules present in the atmosphere, such as carbon monoxide or water. Indeed, each molecule absorbs light at specific wavelengths, which gives it a distinct barcode-like signature. This signature is affected by velocity fluctuations due to the planet’s (very fast!) motion around its star. This is called the ‘Doppler effect’. The star also moves, but much more slowly. it is therefore possible to use this effect to distinguish the signal of the planet from that of the star. I also had the opportunity to work on the development of an algorithm called ATOCA dedicated to the analysis of data from the NIRISS instrument, Canada’s contribution to the famous James Webb Space Telescope. ATOCA will allow us to make the most of the observations obtained by this instrument in order to unravel the mysteries of the atmospheres of various exoplanets. Therefore, my thesis concerns the refinement of data analysis techniques applied to exoplanet atmospheres, both for observations on Earth (with SPIRou) and from space (with JWST). More information Antoine completed his Ph.D. at the Université de Montréal between 2016 and 2022, under the supervision of professors René Doyon and David Lafrenière. His thesis will be available soon. ← New distinction for two young iREx researchers
