Nick Cowan (Northwestern) Poten al for Characteriza on of Transi ng Planets with JWST Study Analysis Group 10 (SAG-X)
1. What is the full diversity of planet proper es needed to characterize and understand the climate of short- period exoplanets? 2. Which measurement suites and how much observing me are needed to characterize the climate of transi ng planets? 3. Will JWST be able to characterize the atmospheres of transi ng terrestrial planets? 4. Which cri cal measurements will be too expensive or inaccessible to JWST, and can these be obtained with planned observatories?
SAG-X Par cipants (so far) Daniel Angerhausen (RPI), Natasha Batalha (Penn State), Adrian Belu (Bordeaux), Knicole Colon (Lehigh), Bill Danchi (Goddard), Pieter Deroo (JPL), Jonathan Fortney (UCSC), Sco Gaudi (Ohio State), Tom Greene (Ames), Ma Greenhouse (Goddard), Joe Harrington (UCF), Lisa Kaltenegger (MPIA), Nikole Lewis (MIT), Chuck Lillie (Lillie Consul ng), Mercedes Lopez-Morales (CfA), Avi Mandell (Goddard), Emily Rauscher (Princeton), Aki Roberge (Goddard), Franck Selsis (Bordeaux), Kevin Stevenson (Chicago), Mark Swain (JPL)
1D Climate Cartoon
Tstrat
Stratosphere
Tropopause
Height Thermal Emission Probes Near Tropopause Γ Troposphere
Reflected Light Probes Near Surface
Temperature Tsurf 1D Climate Cartoon
Increase Insola on and/or Decrease Albedo Height
Temperature 1D Climate Cartoon
Increase Longwave Opacity Height
Temperature 1D Climate Cartoon Height Decrease Specific Heat Capacity
Temperature 2D Climate Cartoon (eg: height + la tude)
Unfortunately we don’t have To learn from exoplanets, robust predic ve models for: we need to measure: • Clouds • Planetary Albedo • Atmospheric Loss Height • Albedo Gradients • Photochemistry • Emi ng Temperature • Geochemical Cycling • Temperature Gradients Advec on • Wind Veloci es (ver cal and horizontal)
Temperature Predic ng vs Measuring Planetary Climate
Model Inputs Model Outputs • Insola on • Emi ng Temperature • Eccentricity • Temperature Gradients • Obliquity • Diurnal Response • Surface Albedo • Seasonal Response • Greenhouse Gases • Cloudiness • Specific Heat Capacity • Surface Temperature • Surface Gravity • • Surface Pressure Precipita on • Thermal Iner a Transit Phase Varia ons Archetypal Short-Period Planets
Hot Earth (CoRoT-7b, Kepler 10b, α Cen Bb)
Temperate Super-Earth (HD 85512 b, GJ 163 c)
Warm Neptune (GJ 1214b, GJ 436b)
Hot Jupiter (HD 209458b, HD 189733b, WASP-12b) Transit Thermal Light Curve Brightness
100%
2 99% Transit Depth = (Rp/R*) Transit
Time Some Transit Depths
Warm Neptune: 2.7E-2
Hot Jupiter: 8.8E-3
Temperate Super-Earth: 7.3E-3
Hot Earth: 7.3E-5 Thermal Light Curve Brightness 2 Annulus/Stellar Area = 2RpH/R* (where scale height H = kBT/μg) 100% Transit 99%
Transit depth is different at different wavelengths
Time Some Transit Spectral Features
Warm Neptune: 2.4E-4
Hot Jupiter: 1.2E-4
Temperate Super-Earth: 6.5E-6
Hot Earth: 2.0E-6 Eclipse Thermal Light Curve
Brightness Star + Planet Star 100.3% 100% Eclipse
Eclipse Depth ≈ (R /R )2 (T /T ) 99% p * day * Transit
Time Some Eclipse Depths
Warm Neptune: 8.1E-3
Hot Jupiter: 4.0E-3
Temperate Super-Earth: 7.0E-4
Hot Earth: 3.3E-5 Thermal Light Curve
Brightness Star + Planet Star 100.3% 100% Transit Eclipse depth is different at different wavelengths 99%
2 Eclipse Spectrum ≈ (Rp/R*) (Tsurf - Ttrop)/T*
Time Thermal Phases Thermal Light Curve
Star + Planet Brightness Star 2 Phase Amplitude ≈ (Rp/R*) (Tday - Tnight)/T* 100.3%
100.1% 100% Eclipse Transit
Time Eclipse Spectroscopy vs. Phase Varia ons
• Differences in temperature – Ver cal (33-200 K) – Zonal (60-2000 K) • Spectroscopy has to achieve S/N with rela vely narrow bandwidth (R>10) • Phase varia ons require long-term stability Predic ng vs Measuring Planetary Climate
Model Inputs Model Outputs • Insola on • Emi ng Temperature • Eccentricity • Temperature Gradients • Obliquity • Diurnal Response • Surface Albedo • Seasonal Response • Greenhouse Gases • Cloudiness • Specific Heat Capacity • Surface Temperature • Surface Gravity • • Surface Pressure Precipita on • Thermal Iner a