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Seminar of Kharkiv Institute of Astronomy

Title: "*Exoplanetary atmospheres with the James Webb Space Telescope*"

Speaker: Dr. *Achrène Dyrek*, CNRS Post-Doctoral Fellow, Astrophysics Department CEA Paris-Saclay

Time: *Tuesday, January 23, 2024, 15:15-16:00*

Abstract:
Our understanding of exoplanet atmospheres is being revolutionised by the observational capabilities of the newly-operating James Webb Space Telescope (JWST). More specifically, the Mid-Infrared Instrument (MIRI) carries out atmospheric photometry and spectroscopy in an uncharted wavelength range between 5 and 28 micro-meters, providing new insights and unexpected molecular detections in exoplanetary atmospheres. In that context, this talk presents the work I have conducted during my thesis as part of the JWST Guaranteed Time Observation (GTO) exoplanet team during the past three years. I will (1) provide the latest updates of the MIRI in-flight performances and on its associated data reduction pipeline, (2) present the most recent discoveries led by the GTO team on a wide variety of planets from brown dwarfs to temperate rocky ones and (3) place the emphasis on the transiting warm Neptune WASP-107b for which the GTO team has conducted the first mid-infrared detection of sulphur dioxide (SO2) and silicate clouds, thus providing evidence of disequilibrium chemistry and active photochemistry in its atmosphere and therefore opening a new window on these close-in worlds.