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Direct imaging of cold exoplanets. Prospects for atmospheric characterization.

Óscar Carrión González
Technische University at Berlin

Upcoming space missions such as WFIRST and concepts like LUVOIR or HabEx will measure the starlight reflected from cold and temperate exoplanets by direct imaging. Reflected starlight is sensitive to atmospheric depths that cannot be probed in transit and provides a means for investigating non-transiting exoplanets. Directly imaged exoplanets observed in reflected starlight represents the next frontier in exoplanet atmospheres characterization. Thus, the theory for planning and interpreting future observations and the physics behind them is now in development.
The goal of this work is to understand what information can be extracted from direct imaging observations of exoplanets in reflected starlight and how robust these conclusions are. Particularly, we focus on Barnard's Star b, a planet candidate announced in 2018 from the analysis of 20 years of radial velocity data of this M dwarf, the second nearest stellar system (d=5.96 ly) after α Centauri. Due to its proximity and given its mass and orbital distance (M·sini=3.23M⊕ ; a=0.4 AU) this planetary system is currently one of the most promising targets for the aforementioned direct imaging missions.
We computed synthetic spectra for more than 3 million possible atmospheric configurations that probe a variety of physical properties of the atmosphere. With that, we studied how degeneracies between parameters affect the atmospheric retrieval and how could we overcome those uncertainties by observing the planet at different phase angles.

2019 November 26, 14:30

Centro de Astrofísica da Universidade do Porto (Classroom)
Rua das Estrelas, 4150-762 Porto

Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia