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Centro de Astrofísica da Universidade do Porto

Towards the characterization of Earth-like exoplanets


Principal investigator
Sérgio A. G. Sousa

The mission CHaracterizing ExoPlanets Satellite (CHEOPS) was recently selected by the European Space Agency (ESA). CHEOPS will be the first mission dedicated to observe exoplanet transits by means of ultra-high precision photometry on bright stars. CHEOPS will derive precise planetary masses and radii for an unprecedented sample of near-by planets allowing to set new constraints on the structure, formation and evolution of low mass planets.

The precise derivation of parameters for the discovered exoplanets, including their masses and radius (and thus mean density, critical to get the bulk composition), is strongly dependent on the knowledge of stellar parameters. For instance, the accuracy on the stellar radius is crucial for an accurate determination of the planet radius from a transit light curve. Precisions of a few percent are fundamental to discriminate different planet compositions (Fressin+2011) and allow to fully make use of the high quality data of future missions such as CHEOPS (as well as TESS and PLATO).

The Science: towards precise planetary parameters

It will be addressed, in unprecedented detail, the problem of deriving precise stellar parameters for planet-host stars, in particular focusing on the complex case of M-dwarf stars, whose stellar parameters are difficult to derive with present day methods. New avenues will be explored for the determination of precise stellar parameters that will allow to characterize with unprecedented detail the properties of the exoplanets. It will also be explored synergies between ESPRESSO and CHEOPS (the team is deeply involved in both instruments/missions). ESPRESSO will allow us not only to detect the best targets but also derive the precise planetary mass, and CHEOPS will allow us to better constrain the planetary radius with unprecedented precision. Together they will allow to infer internal properties of the planets with exquisite precision.

Technical contribution for CHEOPS

The technical contribution for the mission science operation relies on the definition of state-of-the-art data reduction strategies. One of the main goals is the definition and evaluation, from the scientific point of view, of the algorithms that will allow the mission to reach the required precision on data. The data reduction package has responsibility co-shared by CAUP and LAM (Laboratoire d'Astrophysique de Marseille).

Funding institution
Fundação para a Ciência e a Tecnologia

Start: 1 May 2015
End: 30 April 2020

Fundação para a Ciência e Tecnologia

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.

Proceed on CAUP's website|Go to IA website