Transcript Atmosphere
Lecture V: Terrestrial Planets & Summary 1. 2. 3. 4. Plate Tectonics Atmospheres & Spectra Geophysical Cycles Future Exploration Earth’s tectonic plates today Plate tectonics Super-Earth Model Input: M, Psurf, Tsurf, guess R, gsurf, composition Output: R, ρ(r), P(r), g(r), m(r), phase transitions, D, ... Plate tectonics on Super-Earths Plate tectonics - more robust for higher masses: < Thinner plates, stronger stress (Valencia, O’Connell, Sasselov 2007) Super-Earths geochemistry, e.g. the Carbonate-silicate cycle, or Sulfur cycle, etc. Planets of different initial conditions are “driven” to a set of geochemical equilibria by global geo-cycles over geological timescales. e.g., Halevy & Schrag (2008) Atmospheres: A hot Jupiter (51 Peg b) spectrum Seager & Sasselov (2000) Photometric Light Curves Micromagnitude variability from planet phase changes • Space-based: MOST (2005), COROT (2007), Kepler (~2009) • D m=2.5 (Rp/D)22/3/p(sin(a) + (p-a)cos(a)) Scattered Light Need to consider: • phase function • multiple scattering Scattering Phase Functions and Polar Plots MgSiO3 (solid), Al2O3 (dashed), and Fe(s) Forward throwing & “glory” Seager, Whitney, & Sasselov 2000 Scattered Light Changes with Phase 51 Peg @ 550 nm Seager, Whitney, & Sasselov 2000 Atmosphere: What is special about atomic Na and the alkali metals? Seager & Sasselov (2000) Atmosphere: The tricks of transmission spectroscopy: Brown (2001) Atmosphere: Theoretical Transmission Spectra of HD 209458 b Wavelength (nm) Seager & Sasselov (2000) Direct Detection of Thermal Emission Transit & eclipse of HD189733b Heather Knutson & Dave Charbonneau (2007) Spectra Four observed data points vs. models Burrows, Sudarsky, & Hubeny (2006) Spectrum for HD 189733b Inverse Residual Flux Obtained by transit transmission & eclipse emission Wavelength (Swain et al. 2008) New 2 m Spectrum for HD 189733b The “Tree of super-Earths” Super-Earths Terrestrial Planets / Dry, Rocky Planets Fe -rich mantle ? H2O -rich mantle Ocean Planets / Water Planets Mini-Neptunes ? ? ? ? (Sasselov, 2008, Nantes) Theoretical spectra of Super-Earths How to distinguish mini-Neptune from super-Earth: < Three types of atmospheres (Miller-Ricci, Seager, Sasselov 2008)