Presenter: Julia Victoria SEIDEL
Abstract:
The sodium doublet is one of the most powerful probes of exoplanet atmospheric properties, when observed in transmission spectroscopy during transits. Recent high-spectral resolution observations of the sodium doublet in hot gas giants allowed us to resolve the line shape, opening the way for extracting atmospheric properties using line-profile fitting.
I present the MERC code, a tool to interpret high resolution transmission lines via a retrieval method to determine the temperature-pressure profile and the velocity of high-altitude winds in the thermosphere of exoplanets. The curiously broad sodium doublets in HD189733b and similarly in WASP-76b are particularly interesting (Seidel et al. 2019a) and highlight the need for high velocity winds up to the thermosphere in Hot Jupiters.
The method could be applied to the whole sample of planets from the on-going HEARTS & SPADES survey for hot exoplanetary atmospheres at high-spectral resolution with HARPS and HARPS-N, and to the observations with next generation spectrographs like ESPRESSO. With the thus determined temperature-pressure profile and velocity of high-altitude winds I will create a clearer picture of the impact of winds and stellar irradiation on planetary upper atmospheres (Seidel et al. 2019b, in prep.).