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Stellar activity does make exoplanet seem misaligned!

Mahmoudreza Oshagh
Institute for Astrophysics, Georg-August-University of Göttingen, Germany

Stellar active regions, either the occulted or unocculted ones, influence the shape of high-precision transit light curves, and lead to an inaccurate estimate of the planetary parameters. Since the physics and geometry behind the transit light-curve and Rossiter-McLaughlin (RM) effect are the same, the RM observations are expected to be affected by the stellar active regions in a similar way. Oshagh et al. 2016 demonstrated, by using simulations, that inaccurate estimation on the spin-orbit angle owing to stellar activity can be significant (up to 40 degrees). We obtained high-precision RM measurements (performed by HARPS) during several transits of several exoplanets which all transit very active stars. Our results revealed that the impact of activity on the spin-orbit angle can even be larger that the predicted values from simulation, for instance, up to 60 degrees variation in the spin-orbit angle from transit to transit.

2018 July 10, 14:30

Centro de Astrofísica da Universidade do Porto (Auditorium)
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