Lessons for PLATO 2.0 from CoRoT (and Kepler) on follow-up observations
François Bouchy Laboratoire d’Astrophysique Marseille Observatoire de Genève CoRoT transiting candidates Feb 2007 - Nov 2012 26 CoRoT Fields 180’000 stars observed ~ 600 planetary candidates ~ 350 high priority planetary candidates with Follow-Up observations Ground-based photometric follow-up - To estimate dilution factor within photometric mask - To exclude diluted eclipsing binaries with ON-OFF photometry - To identify close contaminant at high angular resolution
1 arcmin
Deeg et al. 2009 Radial velocity follow-up
Main goals: - establish the nature of the transit events - characterize the mass and eccentricity from earth-like planets to brown-dwarfs.
By-product: - Central star spectroscopic parameters - Stellar activity indicators and corrections - Spin-orbit angle measurement (Rossiter-McLaughlin) - Long term follow-up (multiple systems) CoRoT radial velocity facilities
FIES/2.5-m 54 nights HIRES/10-m SOPHIE/1.93-m 26 nights 120 nights
722 meas. on 178 candidates
FLAMES/8.2-m HARPS/3.6-m 4 nights 150 nights Since march 2007 RV obs. on 317 targets among 616 candidates 1405 meas. on 205 candidates Assets of SOPHIE and HARPS for RV follow-up
- High flexibility in the scheduling
- Automatic and real time pipeline at the telescope
- Specific tools available at the telescope : - background moon light correction - bisector span - activity index, vsini, [Fe/H] - CCF masks library A, F, G, K, M
- σRV exposure time calculator
- Daily updated data bases A zoo of false positives Eclipsing M dwarfs
Grazing eclipsing binaries Secondary-only eclipsing binaries
Background eclipsing binaries (inside CoRoT window) Blended eclipsing binaries (inside seeing)
Hot and fast Rotating star ? no signif. RV variations Transiting planets
See A. Santerne’s talk mR < 14.5 80% solved candidates 15 exoplanets Among completed fields : mR > 14.5 516 candidates 55% solved candidates 334 solved 15 exoplanets 30 exoplanets with mass
1 1 6 7 9 6
1.5 2.5 6 15 30 vsini < 2 km/s σRV [m/s] in 1 hour with HARPS on K5V 3.0 5.0 12 30 60 vsini ~ 5 km/s 182 unresolved candidates 30 with flag < 2 and R mag < 14.5
Next step - Identify best remaining candidates - Validate planets with PASTIS see R. Diaz’s talk - RV FU with ESPRESSO@VLT (2016) Kepler transiting candidates
March 2009 - May 2013 1 single field ~156’000 stars 3277 candidates 135 validated planets 40 planets with mass Kepler transiting candidates
Mass characterization Mass upper limit through TTVs with HARPS-North and dynamical studies Photon-noise + 0.8 m/s 2K > 3 sRV
~ 35% of FPP for giant planetary candidates Santerne et al. 2012 Kepler radial velocity facilities
HIRES/10-m HRS/9.2-m FIES/2.5-m SOPHIE/1.93-m
HARPS-N/3.6-m TRES/1.5-m CoRoT + Kepler exoplanets with known mass
Mass determination by TTVs C8b
K4b
K20c K68b Mass characterization K20b by RV meas. C7b K10b
Planetary Mass 2013 FU results on CoRoT and Kepler candidates
KOI-205 SOPHIE
Diaz et al. 2013 Hébrard et al., 2013
Guenther et al. 2013 Almenara et al. 2013 Hot Jupiter Doppler boosting
Faigler et al., 2013 Weiss et al. 2013
Kepler-68b CoRoT 101186644 HARPS Low-mass dense M-dwarf
Gilliland et al. 2013 Kepler-68c
Tal-Or et al. 2013 • RV FU mandatory to characterize accurate mass and eccentricity, and to determine the rate of false positives (often underestimated)
• RV follow-up and mass characterization of small-size candidates penalized by the magnitude of CoRoT and Kepler targets
• Dedicated RV facilities with flexibility and reactivity are crucial
• 2-m class telescopes offer a real efficiency for FU and are complementary to larger telescopes
• Multi-planetary candidates + stellar activity require a huge number of RV measurements
• Brighter targets with PLATO will considerably help the validation and characterization processes