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The CORALIE survey for Southern extra-solar planets *
IV. Intrinsic stellar limitations to planet searches with radial-velocity techniques
S. Udry and
Received 6 April 2000 / Accepted 14 July 2000
Activity related phenomena can induce radial-velocity variations, which can be very important when dealing with extra-solar planet search programmes requiring high-precision radial-velocity measurements.
In this paper we present a new chromospheric activity index, , based on the CaII H line central reemission, and constructed using CORALIE spectra. After one year of measurements, values of are available for a sub-sample of stars of the Geneva extra-solar planet search programme. After transforming the values into the Mount-Wilson "S" scale we obtained values of the CaII H and K flux corrected from photospheric emission () for the stars. The first results are presented, and in particular we focus on the study of the relation between the observed radial-velocity scatter and the chromospheric activity index , for F, G and K dwarfs.
Key words: techniques: radial velocities stars: planetary systems stars: activity stars: starspots
Send offprint requests to: Nuno.Santos@obs.unige.ch
Online publication: September 5, 2000