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Exoplanet Characterization with JWST Jeff Valenti (Space Telescope Science Institute). Exoplanet Characterization with JWST. Investigators: E xoplanet community Scientific Category: Exoplanets Scientific Keywords: Planet formation and evolution Planetary atmospheres
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ExoplanetCharacterization with JWSTJeff Valenti(Space Telescope Science Institute)
Exoplanet Characterization with JWST • Investigators: Exoplanet community • Scientific Category: Exoplanets • Scientific Keywords: • Planet formation and evolution • Planetary atmospheres • Instruments: NIRSpec, MIRI, NIRCam • Proprietary Period: 0-12 months • Requested Allocation: 2600 hours (6% of 5 years) DRAFT – pleasecirculate!
Key Questions • Explore the diversity of planets • Density, Composition, Stratospheres, Eccentricity, … • How do planets form/arrive so close to star? • Signatures of core-accretion processes • Migration and other dynamical processes • Processes that control planetary atmospheres • Cloud formation, non-equilibrium chemistry, etc. • Stellar irradiation • Origin of water
Core-Accretion Scenario Pollack et al. (1996, Icarus, 124, 62) Phase III Giant planet formation via rapid gas accretion Phase II Envelope formation via gradual gas accretion Phase I Core formation via rapid accretion of planetesimals in “feeding zone” Core + Envelope Core Only Isolation Mass
Diverse Formation and Evolution Low Density Exoplanet Diversity High Density Core mass, composition, migration, heating, …
Schematic of Transit and Eclipse Science Eclipse Planet thermal emissionappears and disappears 10-3 Seager & Deming (2010, ARAA, 48, 631) Transit Learn about atmospheric circulation from thermal phase curves Measure size of planet 10-2 See starlight transmitted through planet atmosphere 10-4
Program Goals • Refine planet radius and hence planet density • Atmospheric composition: H, CH4, CO, CO2, H2O, … • Vertical temperature structure, effect of irradiation • Longitudinal temperature structure, heat distribution • Latitudinal temperature structure (grazing eclipses) • Measure small eccentricities transit/eclipse timing • Dependence on planet mass (Jupiter super-Earth) • Constrain formation, evolution, and structure models • Sample stellar surface features (limb, spots, …) • Verify transits of terrestrial planets (e.g. Kepler) • Assess habitability? • Planetary exospheres?
Eclipse Spectroscopy and Photometry IRS IRS MIPS NICMOS Model HD 189733b 2 3 4 20 10 Swain et al., Astro2010 white paper
GJ 1214b Transit Spectrum from the Ground Bean et al. (2010, Nature, 468, 669) R=45 VLT/FORS2
HD 189733b Thermal Emission from the Ground NLTE CH4 ? Swain et al. (2010, Nature, 463, 637)
JWST Instrument Configurations eclipses transits 7 2 4 64 imaging 2 10 33
Thermal Emission versus Orbital Phase HD 189733 b 1210 K 970 K Peak temperature precedes eclipse by 16±6˚ 0.979 transit depth Knutson et al. (2007, Nature, 447, 183) Spitzer, 8 µm, 33 hours
Photometric Precision as Target Drifts Sum of 5x1 pixels Single Pixel Barron et al. (2007, PASP, 119, 466) Charge Diffusion H2RG @ 1.05 µm Not JWST detector
50 Good Targets Today… Want 50 Best for JWST HD 149026 HD 189733 RV Elektra TESS GJ 1214 Kepler CoRot HAT, WASP, XO, …
Transit Study of Cool Atmospheres Good targets from Kepler… better ones coming! Extracted from Bill Borucki’s presentation on Monday. Data from Tome Greene.
Strawman Survey Program Assumes an average of 5 hours / visit