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And now, MoleculesJean Schneider – Paris Observatory

● Why ● Where● How

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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

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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....

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Why

● Why moleculesAfter Mass and orbit and statistics (from RV – astrometry 10-100

times more expensive) Radius from transits

Radius: disentangle atmosphere and solid coreM-R-atmosphere correlation (Elkins-Tanton): insight on

atmosphere origin: degassing /vs accretion

Starting from spectra, disentangle molecules from Haze Clouds Surface (Continents/oceans)

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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

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WherePlenty of candidate super-Earths (Mayor et al 2008):

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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)

R Ring= M pl

d stones

1 /3

~2R pl

Keywords: openmindedness – anticipation of surprises

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Some non standard situations● Rings --> Contribution of ice bands in spectra

Planet cooler in the ring's shadow(Bézard et al 1984): tiny distortionin thermal spectra T

em

p.

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Some non standard situations:artefacts

● Band at 9.6 micron: ozone or Diopside ?

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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 »

How

x(t), y(t)

F t ,

Refining

Rotation periodSurface morphologySurroundings

Time variation A(t)

orbit

d(t)

Tpl « first guess »

A× R pl2 A abs. val.

Rp

l

Primary observables

GAtmospheric 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

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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)

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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:

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HowImplementation: a plan we can believe inMono (-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

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HowImplementationMono (-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

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HowImplementationMono (-pupil -spacecraft) / Multi (-aperture -spacecraft)After RV, transits, continue step by step approach:

1st 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

2nd 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