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