Planetary Planetary CharacterizationCharacterization

Giovanna Tinetti

University College London

- France Allard (CRAL, radiative transfer, spectral models)- Nicole Allard (GEPI, spectroscopy of atomic species)- Alan Aylward et al. (UCL, 3D upper atm. modeling)- Bruno Bezard (LESIA, solar system, models/observations)- James Cho (QMUL, atmosphere dynamics)- Athena Coustenis (LESIA, solar system, models/obs.)- Olivier Grasset (Un. Nantes, planetary interior)- John Harries (Imperial College, Earth mod/obs)- Hugh Jones (Un. of Herthfordshire, exoplanet obs.)- Helmut Lammer (IWF/OeAW, upper atm.)- Emmanuel Lellouch (LESIA, solar system, model/obs.)- Enric Palle (IAC, Earth observations/biosig.)- Heike Rauer et al. (DLR, atmos/biosig. modeling)- Jean Schneider (LUTH, exoplanet observations)- Franck Selsis (Un. Bordeaux, planetary models/biosig.)- Daphne Stam (SRON, exoplanet polarization)- Jonathan Tennyson (UCL, spectroscopy of molecules)- Giovanna Tinetti (UCL, exoplanet spectral simulations)- Yuk Yung (Caltech, photochemistry/rad. transfer)

Projects Spectral Bands

Output Type of Planets

High Accuracy RV Visible/NIR Mass, address, statistics Giant and super-Earths

Cold Spitzer

MIR Photometry and low res. spectroscopy of transiting

planets

Nearby Hot Jupiters and Neptunes, Super-Earths

around M stars?

Warm Spitzer

MIR Photometry at 3.6 and 4.5 micron

Nearby Hot Jupiters and Neptunes, Super-Earths

around M stars?

HST (UV) VIS, NIR Low, Medium, (High) res. Spectroscopy for transiting

planets

Nearby Hot Jupiters and Neptunes, Super-Earths

around M-stars?

SPHERE/GPI (2011) NIR

VIS

Photometry & spectra

Photometry, polarization

Young/massiv e nearby giants

Young/massiv e nearby giants

JWST (2013) NIR-MIR Photometry &

High Res. Spectroscopy transiting planets

Down to Super-Earths & favourable Earth-size Planets;

Habitable zone M-stars

SPICA (2018) (NIR)-MIR-FIR

Low & High Res. Spectroscopy transiting

planets

Down to Super-Earths & favourable Earth-size Planets;

Habitable zone M-stars

ELTs (2018-2020) VIS-NIR Spectroscopy, Photometry, Polarization

Mature giants, super-Earths

Small/medium telescope + Coronograph

(SEE-Coast, SPICA-coronograph, Epic, Peco,

Access etc.)

VIS + (NIR)

MIR

Photometry & spectra & degree of polarization

Photometry & Spectra

Mature giants, nearby super-

Earths

Astrometry / RV with ELT

Visible Mass, address, statistics Earth sized planets, habitable zone

TPF-C VIS (NIR) Low-Medium Res. Spectroscopy ~ 100

Down to Earth sized planets in habitable zone

TPF-O VIS (NIR) Medium Res. Spectroscopy 300-1000

Down to Earth sized planets in habitable zone

TPF-I/Darwin MIR Low-Res. Spectroscopy < 40 Down to Earth sized planets in habitable zone

Atmospheric characterisation: priorities for future missions

• Spectroscopy! • Spectral resolution• Signal to noise reachable• Integration time• Wavelength range• Instrument sensitivity• Redundancies to address degeneracy• Variety of planetary types (Gas-giants, Neptunes, Terrestrial Planets, orbiting different types of stars, @ different orbital separation

• Type of targets reachable

20082008Contribution: advanced.

Low res; spectroscopy from space.

Higher res. from ground?Hot planets orbiting very close

in, Targets down to Super-Earth

UV-IR

~2015-2018~2015-2018JWST, SPICA:

High spectral res. from space, down to ~Earth-size,

planets orbiting close-in,Habitable zone M-stars?

IR

Further into the future:Further into the future:Improved resolution,

sensitivity, broader spectral window etc.

20082008Contribution: study phase.

2010: VLT-Sphere first light (warm Jupiters, large separation)

~2015-2018~2015-2018Small size space-based missions?

E-ELT-EPICS (ground) Low spectral res. ~ 65,

planets with larger separation,down to Super-Earth size,

Habitable zoneVIS-NIR-MIR

Further into the future:Further into the future:Large space-based missions,Planets down to Earth-size,

Habitable zoneHigher spect. resolution

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Transiting planets

The present (Hubble, Spitzer, ground)

Planets orbiting VERY close in +

Photometry/low spectral resolution from space, very high spect. res from ground?

Hot Jupiters, hot Neptunes, hot-Super Earths?

Radial velocity / Occultation

Period = 3.524738 Period = 3.524738 daysdays

Mass = 0.69 ±0.05 Mass = 0.69 ±0.05 MMJupiterJupiter

Radius = 1.35 ±0.04 Radius = 1.35 ±0.04 RRJupiter Jupiter

Density = 0.35 ±0.05 Density = 0.35 ±0.05 g/cmg/cm33

HD 209458bHD 209458b

Sotin, Grasset & Mocquet;

Kuchner & Seager;

Radius/mass ratio

Ice

Silicate

Carbon

Charbonneau et al., 2002

0.0232±0.0057%

First atmospheric component: NaFirst atmospheric component: Na

Sensitive to overall temperature, main atmospheric component, planetary mass

Harrington et al., Science, 2006

υ Andromeda light-curve @ 24

μm

contribution from the planet:

~0.1%

Light curves of a non-transtiting Light curves of a non-transtiting exoplanetexoplanet

VIS-MIR transit VIS-MIR transit spectroscopy spectroscopy

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Swain, Vasisht, Tinetti, Bouwman, Deming, Nature, submitted

Swain et al., 2008aSwain et al., 2008a +Grillmair, 2007

Charbonneau et al., 2008

Knutson et al., 2008

Deming et al., 2007

Knutson et al., 2008

Beaulieu et al., 2008Swain et al., 2008

Pont et al., 2007

d

H2O, CH4, CO + other C-N bearing molecules

The short term future (JWST, SPICA?)

Planets orbiting VERY close in +

High spectral resolution from space

Hot Jupiters, hot Neptunes, hot-Super Earths,hot Earth-size?

Warm Earth-size (Mstar)

Cavarroc, Cornia, Tinetti, Boccaletti, 2008

James Webb Space Telescope James Webb Space Telescope performances (MIRI)performances (MIRI)

Earth-size Planets @ 10, 20, 30 parsec

SPICA

• Japanese (ISAS/JAXA) proposal for successor mission to Spitzer, Akari and Herschel

• Telescope: 3.5m, <5 K

– Herschel: 3.5m, 80K

– JWST: ~6m, ~45K

• Core λ: 5-200 μm

– Δθ=0.35”-14”

• Orbit: Sun-Earth L2 Halo

• Warm Launch, Cooling in Orbit

– No Cryogen → 3.2 t

– Long Lifetime

• Launch: 2017

Primary and secondary transit

photometry/spectroscpy have been shown to be very powerful diagnostic

techniques to probe the atmospheres of extrasolar

planets.

But for planets with larger separation from the Star…

Direct detectionDirect detection

Stellar light reflected by the planet

(UV/visible)

Multiple scattering of reflected photons:Rayleigh scattering/clouds/surface typesMolecules with electronic transitions

Molecules/clouds/surface types

Photons emitted by the planet, Molecules (roto-vibrational modes),

thermal structure, clouds

Photons emitted by the planet

(IR)

Molecules/thermal structure

O3

200 300250

Tropopause

Stratopause

Water Vapor

Ozone Absorption

Absorption

0

10

20

30

40

50

60Net

Emission

In the visible, sunlight is reflected and scattered back to the observer, and is absorbed by materials on the planet’s surface and in its atmosphere.

The planet is warm and gives off its own infrared radiation. As this radiation escapes to space, materials in the atmosphere absorb it and produce spectral features.

VIS - Near VIS - Near IRIR

Molecules in 0.4-2.5 microns

Molecule

Absorption bands (μm)

H2O 0.51, 0.57, 0.61, 0.65, 0.72, 0.82, 0.94, 1.13, 1.41, 1.88, 2.6

CH4 0.48, 0.54, 0.57. 0.6, 0.67, 0.7, 0.79, 0.84, 0.86, 0.73, 0.89, 1.69, 2.3

CO2 1.21, 1.57, 1.6. 2.03

NH3 0.55, 0.65, 0.93, 1.5, 2, 2.3

O3 0.45-0.75 (the Chappuis band)

O2 0.58, 0.69, 0.76, 1.27

CO 1.2, 1.7, 2.4

H2S

VIS: AlbedoVIS: Albedo

Karkoschka, Icarus, 1998

H2O, CH4, NH3, C2H6, CO, H2S, CO2

…

Terrestrial Planet Spectra Vary Widely in Solar System

O2

Iron oxides

CO2

H2O H2O

CO2

EARTH-CIRRUS

VENUSX 0.60

MARS

EARTH-OCEAN

H2O H2O

H2O ice

?

O3O2

VIS-Near-IR signatures for terrestrial planetsVIS-Near-IR signatures for terrestrial planetsin our Solar System in our Solar System

Polarization: a huge help to distinguish

clouds

Polarization variations 10%-40%(Stam et al 2004)

=> Starlight is NOT polarized

Polarization: sensitivity to phase

Polarization variations 10%-40%(Stam et al 2004)

=> Starlight is NOT polarized

IRIR

H2O, CO2, CH4, Hydrocarbons, HCN, H2S, SO2, CO, N2O, NH3 ….

Molecules in the Mid-IR

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Terrestrial Planet Spectra Vary Widely in Solar System

MIR signatures for terrestrial planetsMIR signatures for terrestrial planetsin our Solar System in our Solar System

Knutson et al., Nature, 2007; ApJ, 2008

IR: Thermal structure, IR: Thermal structure, dynamicsdynamics

ESO Extremely Large Telescope-ESO Extremely Large Telescope-EPICSEPICS

EPICS is an instrument project for the direct imaging and characterization of extra-solar planets with the European ELT

• The eXtremeAdaptive Optics(XAO) system - The Diffraction Suppression System(or coronagraph) - The Speckle Suppression System

• The Scientific Instrument(s) - Integral Field Spectroscopy - Differential Polarimetry - A speckle coherence-based instrument

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Missions concepts Missions concepts consideredconsidered

for studies (US)for studies (US)

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Access: coronagraphs for exoplanet missions (John Trauger)

Davinci, Dilute Aperture VIsible Nulling Coron. Imager(Michael Shao)

EPIC: directly imaging exoplanets orbiting nearby stars (Mark Clampin)

PECO: refining a Phase Induced Amplitude Apodization Coronograph (Olivier Guyon)

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M-mission from space or first generation from ground

NWO is a large-class Exoplanet mission that employs two spacecrafts: a “starshade” to suppress starlight before it enters the telescope and a conventional telescope to detect and characterize exo-planets.

Cash, Nature, 2006

The New World Observer

Spectroscopy

O2

H2O

CH4

NH3

S. Seager

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Coronagraph on SPICA

• Assumed observation mode - imaging and low res. spectroscopy - because of limit of sensitivity• Distance/number of target - a few hundred of target in 10pc - a few x 10 seems too small - a few x 1000 is difficult to complete

survey• Wavelength - 3.5-27um rather than 5-27um to detect

excess in spectral, and advantage on IWA.• IWA - limited by coronagraph method. - 3.3 lambda/D (binary mask mode,

baseline of SPICA coronagrah) - 1.2-1.5 lambda/D (PIAA mode)• Contrast - finally 10^-7. To obtain it, 10^-6 for

raw contrast. (~10 is assumed as gain of

subtraction)

Enya et al., Enya et al., 20082008

Direct Detection of Earth-size Planets IR