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Accueil > Séminaires > Archive des séminaires d’Utinam > Archive des séminaires d’astrophysique (jusqu’en 2011) > 2011

The hunt for the escaping atmosphere of a hot neptune

par Edith Burgey -

le jeudi 17 mars a 14 h, salle de conférences de l’Observatoire

par David Ehrenreich, post-doctorant a l’Institut de planétologie et
d’astrophysique de Grenoble (IPAG), Observatoire de Grenoble

Résumé :

Hot neptunes are a class of exoplanets with typical masses around 20x Earth. They are the link between hot gaseous giant exoplanets (or hot jupiters) and super-earths (between 1 and 10 Earth masses). It is surmised that the latters can be evaporation remnants, with atmospheres completely eroded by the extreme stellar irradiation.
Meanwhile, it also appears that hot jupiters are stable with respect to atmospheric evaporation. In this case, what could be the progenitors of hot rocky planets detected by the Corot and Kepler missions ? With their predicted hydrogen/helium envelopes and intermediate masses, hot neptunes are good candidates. Detecting their extended atmospheres and measuring their mass loss rates and atmospheric heating efficiencies are key steps toward the understanding of the atmospheric dynamics and properties of low-mass exoplanets. After an introduction about planetary transits, I will review the results obtained by our group regarding atmospheric evaporation of transiting exoplanets, on both observational and theoretical sides. I will then focus on the case of the hot neptune GJ 436b. I will present Hubble Space Telescope data of this planet’s host star and discuss the prospects about exospheric characterization for exoplanets in the frame of Kepler’s latest announcement of 1000+ transiting planet candidates and the current efforts in which we are involved to confirm and characterize some of these planets.