We have developed a panel of tools to study giant planet atmospheres. These tools have been validated on giant planets Uranus and Neptune. Photochemistry and thermal emission of Neptune's atmosphere were performed in good agreement with literature (Dobrijevic, 1996, Orton et al., 1990). We have also developed a band model to calculate the thermal profiles of giant planet atmospheres. Uranus' calculated profile is in good agreement with observations and was compared to Marley et al.'s results (Marley et al., 1999). The next step of our work is to study the early stages of photochemistry of an extrasolar giant planet atmosphere (age < 109 years). A young star similar to our Sun shows intense UV-flux (I. Ribas, personal communication) which must induce an intense photochemistry from CH4 photolysis. This may alter the composition and infrared emission of the planet's atmosphere. We will present the following results:- an example of the photochemistry of a giant planet -- - a synthetic infrared spectrum of Neptune compared to observed and synthetic ones, -- - a synthetic thermal profile of Uranus, compared to observed and synthetic ones, -- - the evolution of internal heat flows of a giant planet as a function of time and luminosity of its star, -- - the next step of our work: early photochemistry of extrasolar giant planet atmospheres.
SF2A-2003: Semaine de l'Astrophysique Francaise
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