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Disentangling between stellar activity and planetary signals

Boisse, Isabelle ; Bouchy, François ; Hébrard, Guillaume ; Bonfils, Xavier ; Santos, Nuno ; Vauclair, Sylvie

In: Proceedings of the International Astronomical Union, 2010, vol. 6, no. S273, p. 281-285

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    Titre
    • Disentangling between stellar activity and planetary signals
    Auteur
    • Boisse, Isabelle. Institut d'Astrophysique de Paris, Université Pierre et Marie Curie, UMR7095 CNRS, 98bis bd. Arago, 75014 Paris, France email: iboisse@iap.fr
    • Bouchy, François. Institut d'Astrophysique de Paris, Université Pierre et Marie Curie, UMR7095 CNRS, 98bis bd. Arago, 75014 Paris, France email: iboisse@iap.fr
    • Hébrard, Guillaume. Institut d'Astrophysique de Paris, Université Pierre et Marie Curie, UMR7095 CNRS, 98bis bd. Arago, 75014 Paris, France email: iboisse@iap.fr
    • Bonfils, Xavier. Laboratoire d'Astrophysique de Grenoble, Observatoire de Grenoble, Université Joseph Fourier, CNRS, UMR 5571, 38041, Grenoble Cedex 09, France
    • Santos, Nuno. Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
    • Vauclair, Sylvie. LATT-UMR 5572, CNRS & Université P. Sabatier, 14 Av. E. Belin, F-31400 Toulouse, France
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Proceedings of the International Astronomical Union, 2010, vol. 6, no. S273, p. 281-285. Cambridge University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:289963
    Summary
    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 deeper understanding and characterization of the effects of stellar activities 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. We succeed in fitting simultaneously activity and planetary signals on GJ674 and CoRoT-7. We excluded short-period low-mass exoplanets around ι Hor. Our approach is efficient to disentangle reflex-motion due to a planetary companion and stellar-activity induced-RV variations provided that 1) the planetary orbital period is not close to that of the stellar rotation or one of its two-first harmonics, 2) the rotational period of the star is accurately known, 3) the data cover more than one stellar rotational period