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Centro de Astrofísica da Universidade do Porto

Long-term stellar activity and radial-velocity variations of the HARPS M-dwarf sample

J. Gomes da Silva, N. C. Santos, X. Bonfils, X. Dumusque

Abstract.
The relationship between stellar chromospheric activity and variations in the observed radial- velocity (RV) of stars is still an Achilles heel in the Doppler spectroscopy extrasolar planet searches. It is widely known that activity is able to difficult the detection of planets by contributing to noise or even simulate keplerian-like RV signals which might resemble the presence of a companion. Since other stars are known to have magnetic activity cycles similar to that of the Sun and activity variations can be responsible for RV changes, it is extremely important to understand this connection from an exoplanet search point of view. Although, recent studies suggested that these cycles are not related to the RV variations for K-stars at the ~1 m/s level (Santos et al. 2010), this influence is not fully accessed for the case of M-dwarfs, which could behave differently. Here we present the results of such a study for a sample of stars from the HARPS M-dwarf extrasolar planet search program.

Cool Stars 16
Seattle, U.S.A.
August 2010

Type: Poster

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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