GIRAFFE (VLT): A new tool for exoplanets preparatory observations and follow-up Benoît Loeillet (LAM), François Bouchy, Magali Deleuil, Claire Moutou, Jean-Claude Bouret (LAM), Frédéric Royer (GEPI – Paris Meudon),Frédéric Pont (Observatoire de Genève)

GIRAFFE observations Multi-fiber Spectrograph: up to 132 objects Simultaneous Calibration with a Th-Ar lamp R ≈ Survey of 645 stars: 1 spectra each night for 5 nights

Hot Jupiter expected Main Objectives: - Detection of hot Jupiters - Identification of binary stars - Spectroscopic Characterization of stellar population

Targets Observed ● HD HD Field (Anticenter) ● Priority selection based on previous photometric spectral classification (Exodat): F,G,K IV & V ~ 60% III ~ 30% A~10 %) ● mv = 11 → 16

Spectral range: 5150 – 5350 Å m V = 12 → S/N = 100 m V = 14 → S/N = 50 m V = 15 → S/N = 30 In 30 min Exposure time GIRAFFE spectrum

Cross Correlation Method (CCF) Default Correlation Mask ≡ G2V (solar type) Gaussian fit of a CCF gives: –Radial Velocity(km.s -1 ) –FWHM (km.s -1 ) –Contrast (%) Empirical Determination of photon noise uncertainty (Bouchy et al. 05) RV FWHM Contrast

● Less than 10 m.s -1 can be reached for photon noise uncertainty ● A Systematic Error = 50 m.s -1 ● Effort in progress to reduce systematic Instrument Stability 50 m.s -1

SB2 et SB1 Detections Detection of 16 SB2 Easily detected (2 correlation peaks) Detection of 17 SB1 1 peak but high RV Variation

ExoPlanets/brown dwarfs candidates

Conclusion in only 5 half-nights of observations ● 9 exoplanets/brown dwarfs candidates detected in only 5 half-nights of observations. ● BUT need confirmation thanks to SOPHIE (OHP), HARPS (3.6m - ESO), UVES (FLAMES),... ● If confirmed, good candidates for “direct” Over- sampling observation with COROT

● High Potential of the GIRAFFE instrument: efficient detection of binaries and massive exoplanets ● Precision similar to UVES/FLAMES (Bouchy et al., Pont et al. 05 ) ● Possible Follow-up of transiting Hot Jupiter (with known period & phase) ● More efficient than UVES/FLAMES (7 fibers) if alarm rate > 182 detections per COROT Field RV Follow-up Perspectives

THANKS !!