Aurélien Wyttenbach
Observatoire Astronomique de l’Université de Genève

Abstract
Numerous exoplanets are discovered every year. Understanding and observing the atmospheres of exoplanets is one of the major goal in exoplanetology. One way to study exoplanets atmospheres is to use transmission spectroscopy. This technique studies the light filtered through the atmosphere of an exoplanet, as it passes in front of its star (an event named a transit). I explored the possibility to use HARPS, a high-resolution spectrograph in the optical domain, in order to measure exoplanetary transmission spectra. My work established the foundation for an unprecedented use of this instrument. It allowed us to measure, for the first time with a medium-size telescope, some high-resolution transmission spectra of hot Jupiters. When separated from any features of stellar or observational origins, planetary spectrum measurements are very instructive. For example, my studies of sodium lines (via the Fraunhofer D doublet) in the atmospheres of the two hot Jupiters HD189733b and WASP-49b revealed new informations about their thermospheres. Some innovative temperatures and winds measurements in these regions complement the observation made at others wavelengths and resolutions. Henceforth, observations at high-resolution, particularly in the optical domain, are a valuable and important resource in order to understand exoplanets atmospheres.

2017 November 08, 13:30

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto