Gas Giant Planets. III.

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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)
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Outline

• Our own Solar System Jupiter Saturn
• Eroding Jupiters core by convection ?
• The problem with Saturns luminosity
• Helium phase separation
• Evolution models for extrasolar planets
• Helium phase separation as a function of
  planetary mass
• Ice Giant Planets Uranus Neptune

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Interiors of Giant Planets
Jupiters core mass and mass of heavy elements

For MZ - the heavy elements are mixed in
the H/He envelope
Saumon Guillot (2004)
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Interiors of Giant Planets
Saturns core mass and mass of heavy elements

Saumon Guillot (2004)
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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)
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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 x0.085 (solar comp., Y0.27),
  Bconst.(0), A1-2 eV (pressure- dependent
  const.),
• therefore T 5,000 - 10,000 K

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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 !
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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
(Y0.234) Saturn (Y0.2).
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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.
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Evolution Models of Exo-planets
Could the very low-density puffy planets be
heated by phase separation ?

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

Phase separation of other elements Ne, O
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Ice Giants Uranus Neptune
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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)