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Disentangling stellar activity and planetary signals

Author(s): Boisse I. | Bouchy F. | Hébrard G. | Bonfils X. | Santos N.C. | Vauclair S.

Journal: EPJ Web of Conferences
ISSN 2100-014X

Volume: 11;
Start page: 02005;
Date: 2011;
Original page

Photospheric stellar activity (i.e. dark spots or bright plages) might be an important source of noise and confusion in the radial-velocity (RV) measurements. Radial-velocimetry planet search surveys as well as follow-up of photometric transit surveys require a deep understanding and precise characterization of the effects of stellar activity, in order to disentangle it from planetary signals. We simulate dark spots on a rotating stellar photosphere. The variations of the RV are characterized and analyzed according to the stellar inclination, the latitude and the number of spots. The Lomb-Scargle periodograms of the RV variations induced by activity present power at the rotational period Prot of the star and its two-first harmonics Prot/2 and Prot/3. Three adjusted sinusoids fixed at the fundamental period and its two-first harmonics allow to remove about 90% of the RV jitter amplitude. We apply and validate our approach on four known active planet-host stars: HD 189733, GJ 674, CoRoT-7 and ι Hor.
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Tango Jona
Tangokurs Rapperswil-Jona