Lecture V: Terrestrial Planets &Summary

1. Plate Tectonics2. Atmospheres & Spectra3. Geophysical Cycles

4. Future Exploration

Earth’s tectonic plates today

Plate tectonics

Super-Earth ModelInput: 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 differentinitial conditionsare “driven” to aset of geochemicalequilibria by global geo-cyclesover geologicaltimescales.

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)

• m=2.5 (Rp/D)22/3/(sin() + (-)cos())

Scattered Light

Need to consider:• phase function• multiple scattering

Scattering Phase Functions and Polar Plots

Seager, Whitney, & Sasselov 2000Forward throwing & “glory”

MgSiO3 (solid), Al2O3 (dashed), and Fe(s)

Scattered Light Changes with Phase

Seager, Whitney, & Sasselov 200051 Peg @ 550 nm

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)

Occ

ulte

d A

rea

(%)

Seager & Sasselov (2000)

Direct Detection of

Thermal Emission

Transit & eclipse of HD189733b

Heather Knutson & Dave Charbonneau (2007)

SpectraFour observeddata points vs.

models

Burrows,Sudarsky, &Hubeny (2006)

Spectrum for HD 189733bObtained by transit transmission & eclipse emission

Wavelength

Inve

rse

Res

idua

l Flu

x

New 2 m Spectrum for HD 189733b

(Sw

ain

et a

l. 2

008)

The “Tree of super-Earths”S

uper

-Ear

ths

Mini-Neptunes

OceanPlanets /WaterPlanets

TerrestrialPlanets /Dry, RockyPlanets

Fe -richmantle

?H2O -richmantle

?

?

?

?

(Sasselov, 2008, Nantes)

Theoretical spectra of Super-EarthsHow to distinguish mini-Neptune from super-Earth:

< Three types of atmospheres

(Miller-Ricci, Seager,Sasselov 2008)