1. Molecules 081 And now, Molecules Jean Schneider – Paris Observatory ● Why ● Where ● How

2. Molecules 082 And now, Molecules ● Why molecules After mass, orbit, radius, « adresses » and statistics molecules gives the real characterization of exoplanets. Only part of more general approach: spectra, images  Atmosphere, Ground surface  Whole planetary system ● Where (which type of planets) ● How:  Multiple approaches ● Reflected light vs/ thermal emission ● Polarization ● Time variation ● « Inverse problem »  Implementation

3. Molecules 083 Molecules: where do we stand? « Business as usual »:  Plenty of known molecules: Na, CO, CO2, H20, CH4, HCN, H, O, TiO, VO  Gradients  Orbital evolution  Secondary transits (Knutson) Beyond standard situations: rings, artefacts, degeneracies....

4. Molecules 084 Why ● Why molecules After  Mass and orbit and statistics (from RV – astrometry 10-100 times more expensive)  Radius from transits Radius: disentangle atmosphere and solid core M-R-atmosphere correlation (Elkins-Tanton): insight on atmosphere origin: degassing /vs accretion Starting from spectra, disentangle molecules from  Haze  Clouds  Surface (Continents/oceans)

5. Molecules 085 Why After RVs, other approaches to investigate planets: ● Transits: first molecules (Charbonneau), but  Only 1% – 10% of planets  Only brief snapshot along the orbit (~0.1% - 0.5%) ● Astrometry:  No information on the physics of planets

6. Molecules 086 Where Plenty of candidate super-Earths (Mayor et al 2008):

7. Molecules 087 Some non standard situations ● Oxygen on icy bodies (Farmer et al. 2007) --> abiotic oxygen on icy satellites of planet with liquid water ? ● Rings: significant contribution to spectra (ice, CH4) but very different temperature 3 M_Earth 3 M_Jup Ice Rock Ice Rock -------------------------------------------- R_Ring = 2.5 3 R_Earth 3 4 R_Jup ● Hyper-Ios (Briot 2008) Keywords: openmindedness – anticipation of surprises

8. 8 Some non standard situations ● Rings --> Contribution of ice bands in spectra Planet cooler in the ring's shadow (Bézard et al 1984): tiny distortion in thermal spectra Temp.

9. Molecules 089 Some non standard situations: artefacts ● Band at 9.6 micron: ozone or Diopside ?

10. Molecules 0810 Some non standard situations Previous surprises: ● Orbits:  Very close to parent star  Eccentricity ● Too large radius of HD 209458 b ● Why HD 209458 b and HD 189733 b so different? ● Mass-temperature anomaly for 2M 053-054 BD binary The more massive has the lowest temperature (Stassun et al 2007) ● Fomalhaut b (Clampin this Meeting):  Unexplained photometric variability  Unexpectedly large flux « There is nothing like an average planet » (G. Laughlin) ==> « planeto-diversity »

11. How x(t), y(t) Refining Rotation period Surface morphology Surroundings Time variation A(t) orbi t d(t ) T pl « first guess » A abs. val. RplRpl Primary observables G Atmospheric gases Spectrum A(λ ) Rayleigh scattering It is not sufficient to « passively » take spectra of atmopheres. It is also important to decipher them, i.e. extract a planet model. Full deciphering codes yet to be built

12. Molecules 0812 How By-products of molecules by direct imaging:  Mass of planets: ● From measuring orbital inclination + RV ● From gap sculpturing in disks (Fomalhaut: Chiang et al 2008)  Removing degeneracies from RV or astrometry orbital solutions: ● Trojan planets ● 1:2 resoances /vs eccentric orbits ● « exchange orbits » (2 planets on quasi-identical orbits)  Doppler shift relative to star: ==> improve detection, planet mass (Riaud et al 2007)  Benefits of continuous monitoring: ● Rings ● Moons ● Planet rotation (Palle et al 2008)

13. Molecules 0813 How ● One single approach not sufficient to remove degeneracies in extracting planet models from observables ● « Inverse problem »: from observable to planet model ● ==> necessity to accumulate observations: in time, in wavelength range ● But no reason to wait for readiness of all approaches, start with the easiest==> step by step progression Galileo: Today:

14. Molecules 0814 How Implementation: a plan we can believe in Mono (-pupil -spacecraft) / Multi (-aperture -spacecraft) After RV, transits, continue step by step approach: Mono pupil and spacecraft + coronagraph VIS ● ELTs. Problems: - share with cosmology, RV, etc. - not possible of continuous monitoring ==> only few snapshot spectra ● 1.5 – 2 m dedicated space telescope Multi spacecraft Mono -pupil - External occulter - Fresnel array UV, VIS 2 S/C Multi-aperture - Nulling interferometer - Hypertelescope + coronagraph IR 4-5 S/C VIS > 30 S/C Large (4+m) monopupil space corono. Multi-aperture precursor ? ● Nulling interferometer IR

15. Molecules 0815 How Implementation Mono (-pupil -spacecraft) / Multi (-aperture -spacecraft) After RV, transits, continue step by step approach: Mono pupil and spacecraft + coronagraph ● ELTs. Problems: - share with cosmology, RV, etc. - not possible of continuous monitoring ==> only few snapshot spectra ● 1.5 – 2 m dedicated space telescope Multi spacecraft Mono -pupil ● External occulter ● Fresnel array Multi-aperture ● Nulling interferometer ● Hypertelescope + coronagraph Large (4+m) monopupil space corono. 1993-4: TOPS (NASA) 1996: ExNPS (NASA) 1997: ESO WG on Exoplanets Origins Roadmap (NASA) 2005: Cosmic Vision (ESA) ESA-ESO Report on Exopl. 2007: ExoPTF (NASA/NSF) 2008: JPL « Community Report » 2009: EPRAT (ESA) EXOPAG (NASA) Decadal Survey (US Acad Sci)... ad vitam aeternam ? 51 Peg HD 209458 transit CoRoT launch

16. Molecules 0816 How Implementation Mono (-pupil -spacecraft) / Multi (-aperture -spacecraft) After RV, transits, continue step by step approach: 1 st step: Mono pupil and spacecraft + coronagraph ● ELTs. Problems: - share with cosmology, RV, etc. - not possible of continuous monitoring ==> only few snapshot spectra ● 1.5 – 2 m dedicated space telescope 2 nd step: Multi spacecraft Mono -pupil ● External occulter ● Fresnel array Multi-aperture ● Nulling interferometer ● Hypertelescope + coronagraph Large (4+m) monopupil corono. Action! World-wide coordination needed