Lecture IV: Terrestrial Planets 1.From Lecture III: Atmospheres 2.Earth as a planet: interior & tectonics. 3.Dynamics of the mantle 4.Modeling terrestrial planets

Observations for Reflected Light Sudarsky Planet types –I : Ammonia Clouds –II : Water Clouds –III : Clear –IV : Alkali Metal –V : Silicate Clouds Predicted Albedos: –IV : 0.03 –V : 0.50 Sudarsky et al Picture of class IV planet generated using Celestia Software

Lunar Transit of Earth Compare the albedo of the Moon to the Earth’s features, e.g., the Sahara desert. NASA EPOXI spacecraft (2008)

HD b: Albedos New upper limit on A g Rowe et al.(2006) (Rowe et al. 2008)

Models Constraints sigma limit – or - ~ sigma limit Spitzer Limit Different atmospheres blackbody model Rowe et al Rowe et al. (in prep) best fit Equilibrium Temperature

The Close-in Extrasolar Giant Planets Type and size of condensate is important Possibly large reflected light in the optical Thermal emission in the infrared Seager & Sasselov 2000

Scattered Light Need to consider: phase function multiple scattering

Scattering Phase Functions and Polar Plots Seager, Whitney, & Sasselov 2000 Forward throwing & “glory” MgSiO 3 (solid), Al 2 O 3 (dashed), and Fe(s)

Mission  Microvariability and Oscillations of STars / Microvariabilité et Oscillations STellaire  First space satellite dedicated to stellar seismology  Small optical telescope & ultraprecise photometer  goal: ~few ppm = few micromag MOST at a glance Canadian Space Agency (CSA)

 circular polar orbit  altitude h = 820 km  period P = 101 min  inclination i = 98.6º  Sun-synchronous  stays over terminator  CVZ ~ 54° wide  -18º < Decl. < +36º  stars visible for up to 8 wks  Ground station network  Toronto, Vancouver, Vienna MOST at a glance MOST orbit normal vector to Sun CVZ = Continuous Viewing Zone Orbit

Lightcurve Model for HD b Relative depths –transit: 2% –eclipse: 0.005% Duration –3 hours Phase changes of planet Phase Relative Flux Eclipse Transit

Lecture IV: Terrestrial Planets 1.Earth as a planet: interior & tectonics. 2.Dynamics of the mantle 3.Modeling terrestrial planets

Earth’s interior PREM = Preliminary Reference Earth Model

Earth as a planet - tectonics

Earth - plate collision & subduction Kustowski et al.(2006) Evidence from seismic tomography for the subduction of the plate under Japan. Variations in shear-wave velocity:  v S /v S

Earth - the Core-Mantle Boundary

Earth mantle convection simulation Labrosse & Sotin (2002)

Earth interior - mantle plumes

Earth interior - cooling

Super-Earths

Super-Earths: planets in the mass range of ~1 to 10 M E 1.Mass range is now somewhat arbitrary Upper range corresponds approx to a core that can accrete H 2 gas from the disk. 2.Two generic families - depending on H 2 O content. 3.No such planets in our Solar System. (Discussed at Nantes Workshop - June 16-18, 2008)

Formation and survival of large terrestrial planets: Interiors of Super-Earths Ida & Lin (2004) All evidence is that they should be around:

The “Tree of super-Earths” Super-Earths Mini-Neptunes Ocean Planets / Aqua Planets Terrestrial Planets / Dry, Rocky Planets Fe -rich mantle ? H 2 O -rich mantle ? ? ? ?

Super-Earth Model Input: M, P surf, T surf, guess R, g surf, composition Output: R, ρ(r), P(r), g(r), m(r), phase transitions, D,...

Interior Models: the Mass Dependence Zero-temperature spheres Zapolsky & Salpeter (1969); Stevenson (1982); Fortney et al. (2007); Seager et al. (2007) (GJ 436b: Gillon et al. 2007)

Interior Structure of Super-Earths Valencia, Sasselov, O’Connell (2006)

Interior Structure: Radius & Composition Valencia, Sasselov, O’Connell (2007)

Phase Diagram of H 2 O

Super-Earths Mass range: ~ Earth mass “Confusion region”

‘Toblerone’ Diagram A tool to infer which compositions fit M and R with uncertainties M±ΔMM±ΔM R±ΔRR±ΔR Valencia et al. 2007b

Degeneracy is important Si/Fe = 0.6 Si/H 2 O = 0.23 RPRP

Models vs. Kepler observations Valencia, Sasselov, O’Connell (2007)

Earth is a ‘perovskite’ planet Tiny amount of post-perovskite at the CMB (the thin D” region) (Fe, Mg) SiO 3 - enstatite - perovskite (Pv) 40% of Earth is Pv ! - post-perovskite (pPv) Pv pPv at ~125 GPa Super-Earths are ‘post-perovskite’ planets.

Super-Earths as post-Perovskite planets T-P curves for 7.5 M E models < Note: all mantles have pressures that reach 1000 GPa (Valencia, Sasselov, O’Connell 2007)

Super-Earths: very high pressures

Post-Perovskite

Super-Earths as post-Perovskite planets (Oganov 2006) Does post-perovskite incorporate more Fe ? Is there a post-post perovskite, e.g. like GGG ? Are there analogs to the Pv lower mantle ‘oxygen pump’ ? Pv pPv

Post- Post-Perovskite ? Expectation that all (Si, Al, Mg, Fe) oxides will collapse to an O 12 perovskite structure, like Gd 3 Ga 5 O 12 (GGG) does at >120 GPa. < above 150 GPa becomes less compressible than diamond ! (Mashimo, Nellis, et al. 2006)

Z-Beamlet target chamber of 10TWcm -2 setup at SNL (J.Remo, S.Jacobsen, M.Petaev, DDS) (2008) New high-P experiments needed

T-P: Experimental Results (Remo et al. 2008)

We measure 10-50x Fe, Cr, Al -enrichments of the silicate melts (Rightley et al. 1996)  Strong mixing occurs due to a Richtmeyer-Meshkov instability behind the shock - is it scalable & relevant to giant impacts ?

Interiors of Super-Earths Valencia, Sasselov, O’Connell (2006) Earth-like Ocean Planet

Mass-Radius relations for 11 different mineral compositions (Earth-like): Interiors of Super-Earths Valencia, O’Connell, Sasselov (2005) 1M E 2M E 5M E 10M E

Theoretical Error Budget: Planet Radius Errors:  New high-P phases, e.g. ice-XI: -0.4%  EOS extrapolations (V vs. BM): +0.9%  Iron core alloys (Fe vs. FeS): -0.8%  Viscosity, f(T ) vs. const.: +0.2%  Overall the uncertainties are below 2% (at least, that’s what is known now)

Interior Structure of GJ 876d 20,000 12,000 4,000 2,0006,00010,000 RADIUS (km) DENSITY (kg/m 3 ) Valencia, Sasselov, O’Connell (2006) 7.5 M E

Interior Structure of GJ 876d Valencia, Sasselov, O’Connell (2006)

What would we look for and could we measure it ? Could we measure the difference? - YES: We need at least 5% in Radius, and at least 10% in Mass. Work on tables for use with Kepler underway - masses 0.4 to 15 M E

Degeneracy - solution: samples max radius min radius H2OH2O All you need to constrain planet formation models! - sample with radii to 5% and masses to 10%.

Dry vs. Ocean super-Earths Valencia, Sasselov, O’Connell (2007)