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Tuesday 27 Jun 2017Cloud formation and evolution in hot Jupiter atmospheres

Stefan Lines - University of Exeter

4th Floor Interaction Area 11:15-11:45

Recent HST observations of hot Jupiter atmospheres have revealed a continuum in atmospheric

composition from cloudy to clear skies. The presence of clouds is inferred from a grey

opacity in the near-IR that mutes key absorption features in the transmission spectra. This

observational challenge inhibits the retrieval of key information including the atmospheric

chemical composition and thermal structure. Unlike the L-T Brown Dwarf sequence, this

transition does not correlate well with equilibrium temperature, suggesting that a cloud formation

scheme more comprehensive than simply considering the condensation temperature

needed for homogenous cloud growth, is required. In this talk, we follow and extend the

pioneering study of Lee et al., (2016) by performing 3D simulations of cloud nucleation,

growth, advection, evaporation and gravitational settling in the atmospheres of HD209458b

and HD189733b using the kinetic and mixed-grain cloud formation code DIHRT, coupled

to the Met Office GCM, the ’Unified Model’. We explore cloud composition, vertical structure

and particle sizes, as well as highlighting the importance of the strong atmospheric

dynamics seen in tidally locked hot Jupiters on the evolution and distribution of the cloud.

The completeness of the radiative transfer (i.e. inclusion of scattering) and the dynamics

provided by our new model, will represent the most physically complete theoretical tool for

the study of hot Jupiters.

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