Presentation on theme: "Colors of Alien Worlds from Direct-Imaging Exoplanet Missions Renyu Hu Hubble Fellow Jet Propulsion Laboratory California Institute of Technology With."— Presentation transcript:
Colors of Alien Worlds from Direct-Imaging Exoplanet Missions Renyu Hu Hubble Fellow Jet Propulsion Laboratory California Institute of Technology With thanks to Wesley Traub (JPL)
Cool Giant Exoplanets Hu 2014 Type and location of clouds depend on Atmospheric composition Thermal evolution history and beyond 1-D models Updraft and downdraft Deep liquid water clouds dissolving ammonia
Direct-imaging exoplanet missions may offer the capability to broadly distinguish H 2 -rich giant exoplanets versus H 2 O-rich super-Earth exoplanets, and to detect ammonia and/or water clouds and methane gas in their atmospheres Renyu Hu, 2014, Ammonia, Water Clouds and Methane Abundances of Giant Exoplanets and Opportunities for Super-Earth Exoplanets, Report delivered to the EXEP (arXiv:1412.7582) Pressure of Ammonia or Water Clouds Relative strength between the strong and weak bands of methane Abundance of Methane Strength of the methane bands H2O-rich Super Earths High clouds and low methane abundances Conclusion
What do optical phase curves tell us about exoplanets?
Phase Curve of Kepler-7 b Demory et al. 2013 A g =0.35±0.02 Phase offset
Two Scenarios Hu et al. 2015 Planetary Flux = Thermal Emission + Symmetric Reflection + Asymmetric Reflection
Hu et al. 2015 Homogeneous Atmosphere Phase offset attributed to thermal emission A B =0.18±0.03 T photo /T eq =1.23±0.02 t rad /t adv =-0.32±0.05 Patchy Cloud Phase offset attributed to reflection A B =0.42±0.01 r clear <7% r cloudy >80% Cloud boundary 11±3° to the west (cloud condenses at 1500 – 1700 K)
Two Solutions for a Phase Offset Hu et al. 2015 How to break the degeneracy? Measure the planet’s flux at a longer wavelength Modeling atmospheric circulation
Phase offsets are common! Shporer & Hu 2015, submitted
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