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GIRAFFE (VLT): A new tool for exoplanets preparatory observations and follow-up Benoît Loeillet (LAM) ,

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.

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GIRAFFE (VLT): A new tool for exoplanets preparatory observations and follow-up Benoît Loeillet (LAM) ,

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  1. 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)

  2. GIRAFFE observations Multi-fiber Spectrograph: up to 132 objects Simultaneous Calibration with a Th-Ar lamp R ≈ 25000 Survey of 645 stars: 1 spectra each night for 5 nights

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

  4. Targets Observed • HD 49454 - HD 49933 Field (Anticenter) • Priority selection based on previous photometric spectral classification (Exodat): F,G,K IV & V ~ 60% III ~ 30% A~10 %) • mv = 11 → 16

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

  6. FWHM Contrast RV 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)

  7. Instrument Stability • 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 50 m.s-1

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

  9. ExoPlanets/brown dwarfs candidates

  10. Conclusion • 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

  11. RV Follow-up Perspectives • 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

  12. THANKS !!

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