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Classifying the Range of Exoplanetary Atmospheres using Transmission and Emission Spectroscopy

Final Report Summary - CREATES (Classifying the Range of Exoplanetary Atmospheres using Transmission and Emission Spectroscopy)

This project used a twofold approach to advance both the theory and observation of exoplanets beyond their current limitations. The hot Jupiter atmospheric spectra built upon two large observational survey programmes headed by Dr. Sing, one large programme uses the Hubble Space Telescope which is augmented by a large ground-based telescope programme. Both large programmes are further complemented by followup observations, as well as existing near-IR spectroscopy from HST and Spitzer. This project aimed at combing the data in a coherent fashion, enabling studies of nearly the entire planetary atmosphere, including both the lower, middle and upper atmospheres as well as dayside and terminator regions. These observational efforts were combined with a broad and inclusive theoretical modelling programme, aimed at incorporate a full range of crucial physical effects together, including notably clouds and hazes, modelling the complete atmosphere in a self-consistent manner with a 3D global circulation model. The observational results provided a legacy set of transmission spectra across the wide hot-Jupiter exoplanetary class. The project aimed at two key scientific contributions, addressing why some hot Jupiters have hazes & clouds while others do not, finding exoplanet atmospheres exhibit a wide continuum of cloudiness due to the rich variety of condensate cloud materials and high sensitivity to the local temperatures (Sing et al. 2016, Nature). The second key contribution addressed the outstanding issue on the presence or absence of exoplanet stratospheres, where we found the first solid evidence for the presence of a stratosphere and water emission features (Evans, Sing et al. 2017, Nature). A major goal of the programme was to develop the comparative exoplanetary atmospheric science; and for the first time a uniform and comprehensive set of high quality exoplanet spectra are now available on our online Library which can be used to inter-compare exoplanet spectra.