Schedule Apr 02, 2010
Water Clouds and the Search for Cold Exoplanets
Mark Marley (NASA/Ames)

Mark Marley1, Jonathan Fortney2, Didier Saumon3
1. NASA Ames Research Center, Stanford, CA, United States.
2. University of California Santa Cruz, Santa Cruz, CA, United States.
3. Los Alamos National Laboratory, Los Alamos, NM, United States.

As direct imaging searches for cold extrasolar giant planets, including GPI and SPHERE and eventually several instruments on JWST, begin to get underway and with the discovery of what may be one such planet orbiting Fomalhaut, our attention is again turned to the model thermal emission spectra of these planets. Of particular interest is the impact of water clouds that will be found in planets with effective temperatures below about 350 K. Given the abundance of water—especially in enhanced metallicity planetary atmospheres—clouds dramatically affect planetary thermal emission spectra in the near- and mid-infrared. We will report on our exploration of the effect of water clouds with varying properties on model giant planet spectra and discuss how these results might impact the planned observational searches. As is the case with the clouds of Jupiter and Saturn and probably the silicate and iron clouds in the atmospheres of brown dwarfs, horizontal patchiness may be important in exoplanet atmospheres and we consider this effect as well.

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