1. Some of the Hot Jupiters do not match well models based on Jupiter & Saturn: Gas Giant Planets. III. Gaudi (2005) & Charbonneau et al (2006) w Bodenheimer et al.(2003), Laughlin et al. (2005) models; and Burrows et al. (2003)

2.  Our own Solar System: Jupiter & Saturn  Eroding Jupiter’s core by convection ?  The problem with Saturn’s luminosity  Helium phase separation  Evolution models for extrasolar planets  Helium phase separation as a function of planetary mass  Ice Giant Planets: Uranus & Neptune Outline

3. Jupiter’s core mass and mass of heavy elements : Interiors of Giant Planets Saumon & Guillot (2004) For M Z - the heavy elements are mixed in the H/He envelope

4. Saturn’s core mass and mass of heavy elements : Interiors of Giant Planets Saumon & Guillot (2004)

5. Its current luminosity is ~50% greater than predicted by models that work for Jupiter: A Problem with Saturn ?... Fortney & Hubbard (2004) Saturn reaches its current T eff (luminosity) in only 2 Gyr !

6.  The only promising idea for resolving the discrepancy - phase separation of neutral He from liquid metallic H (Stevenson & Salpeter 1977): for a saturation number fraction of the solute (He), phase separation will occur when the temperature drops below T : x = exp (B - A/kT) where x=0.085 (solar comp., Y=0.27), B=const.(~0), A~1-2 eV (pressure- dependent const.), therefore T = 5,000 - 10,000 K A Problem with Saturn ?…

7. Phase diagram for H & He: A Problem with Saturn ?... Fortney & Hubbard (2004) Model results: Stevenson (‘75) vs. Pfaffenzeller et al. (‘95) - different sign for dA/dP !

8. New models: A Problem with Saturn ?... Fortney & Hubbard (2004) Model results: The modified Pfaffenzeller et al. (‘95) phase diagram resolves the discrepancy. Good match to observed helium depletions in the atmospheres of Jupiter (Y=0.234) & Saturn (Y~0.2).

9. Cooling curves: Evolution Models of Exo-planets: Fortney & Hubbard (2004) Models: All planets have 10 M E cores & no irradiation. The models with He separation have ~2 x higher luminosities.

10. Could the very low-density “puffy” planets be heated by phase separation ? Evolution Models of Exo-planets: Phase separation of other elements Ne, O

11. Could the very low-density “puffy” planets be heated by phase separation ? Evolution Models of Exo-planets: Phase separation of other elements Ne, O

12. Ice Giants: Uranus & Neptune

13. Conclusions  Sizes of extrasolar planets are already precise  beware of biases & systematic errors  Models are based on Jupiter & Saturn  Perhaps, Hot & Very Hot Jupiters are more Z enriched:  because of history - excessive migration through disk, or  because of orbit - manage to capture more planetesimals ?  Implications for the core-accretion model:  it requires at least ~6 M E for M core of Jupiter & Saturn  invoke Jupiter core erosion (e.g. Guillot 2005),  use the He settling for Saturn (Fortney & Hubbard 2003)