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Gas Giant Planets. III.

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

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Gas Giant Planets. III.

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

  2. Outline • 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

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

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

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

  6. A Problem with Saturn ?… • 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

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

  8. A Problem with Saturn ?... New models: 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. Evolution Models of Exo-planets: Cooling curves: Fortney & Hubbard (2004) Models: All planets have 10 ME cores & no irradiation. The models with He separation have ~2 x higher luminosities.

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

  11. Evolution Models of Exo-planets: Could the very low-density “puffy” planets be heated by phase separation ? 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 ME for Mcore of Jupiter & Saturn invoke Jupiter core erosion (e.g. Guillot 2005), use the He settling for Saturn (Fortney & Hubbard 2003)

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