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Tuesday 01 Aug 2017Giant exoplanets and their clouds with HST and JWST

Hannah Wakeford - University of Exeter

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

Deciphering the role of clouds is central to our understanding of exoplanet atmospheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Comparative exoplanetology studies with HST present a startling diversity in in atmospheric transmission spectral features, where clouds are shown to mute and obscure atomic and molecular absorption features. However, all is not lost, while compositional information is masked in the optical and near-infrared, enhanced scattering profiles can be used to constrain cloud particle sizes giving insight into local atmospheric dynamics. At temperatures greater than 1200 K refractory condensate species will dominate cloud compositions. Using their optical properties and Mie theory transmission spectra for each condensate can be approximated for a given particle distribution and position in the atmosphere. Vibrational mode features of the main diatomic bonds have been shown to be prominent when the clouds are composed of small sub-micron sized particles and can be associated with an accompanying optical scattering slope. These features are most prominent in the infrared and have potential implications for future exoplanetary atmosphere studies conducted with JWST, where such vibrational modes distinguishing condensate species can be probed at longer wavelengths. 

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