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Centro de Astrofísica da Universidade do Porto
Mapping clouds of exoplanets

Antonio Garcia Muñoz

Accurate visible-wavelength, broadband photometry of spatially unresolved exoplanet + star systems is setting key constraints on various aspects of close-in exoplanet atmospheres (geometric albedos, peak brightness offsets) through the investigation of planetary phase curves [1-3]. To date, this is the approach that has been enabled for a handful of exoplanets by COROT and Kepler. In the incoming years, CHEOPS, PLATO and TESS will greatly expand the number of available exoplanet phase curves, thus allowing for comparative studies amongst a larger planet sample. A theoretical framework to investigate such phase curves and the information contained in them is still missing. We have set out to establish such a framework, and to make the connection between the fundamental properties of exoplanet atmospheres (cloud spatial distribution, optical depth, cloud particle scattering properties) and observable phase curves. Our framework relies on a recently devised backward Monte Carlo algorithm [4-5] that solves the full radiative transfer problem in the three-dimensional atmosphere for user-specified atmospheric configurations, i.e. without assuming Lambertian reflection of the planet or similarly simplified treatments. The algorithm is ideally suited for this problem because it computes the phase curves of inhomogeneous planets without any computational overhead with respect to the solution for homogeneous planets. In the presentation, we show which atmospheric properties could be derived from exoplanet phase curves, and emphasize possible degeneracies between key atmospheric parameters. We use our results to explore the parameter space that future exoplanet GCMs equipped with cloud prediction capacities will need to consider.

17 March 2015, 14:30

Centro de Astrofísica
Rua das Estrelas
4150-762 Porto

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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