Playing with Fire: Thermal Escape from Hot Extrasolar Planets
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Associate Staff Scientist
Lunar and Planetary Laboratory
The discovery of over 200 close-in extrasolar giant planets orbiting their host stars at distances of less than 0.1 AU is one of the big surprises in astronomy of the last two decades. This discovery raised important general questions about mass loss under strong stellar irradiation. The atmospheres of hot giant planets are obviously very different from the atmospheres of the cool giant planets in the solar system. I will highlight some of the key differences by using observations and models to derive a fairly comprehensive picture of the middle and upper atmospheres of moderate hot giant planets such as HD209458b. Based on this picture, I will describe plans for future work on characterizing exoplanet atmospheres. I will also explore the complex interplay between photochemistry and radiative transfer that controls the thermal escape mechanism and mass loss from planetary atmospheres, showing that the evolution of the majority of known transiting giant planets should not be significantly affected by mass loss. This may not, however, be the case for a new class of extremely close-in planets such as WASP-12b. I will present preliminary results for the atmospheres of extremely close-in planets and identify three planets with the highest mass loss potential among commonly studied transiting planets.