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11/24/09
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Neptune migration
Neptune scatters planetesimals increase in eccentricity end up under the influence of J, S scattered out of solar sytem net fffect is that N scatters material inward and migrates outward.
Fernandez & Ip 1986
Tsiganis et al. 2005
Giant Planet Atmospheres and Spectra Atomic/Molecular Abundances
For a given temperature, pressure, composition model the Gibbs free energy
H, He, Li, Na, K, Rb, Cs, Al, Ca, Fe, MgH, H2, CO, SiO, CH4,…
Calculate mixing ratios
Mixing fractions
Burrows & Orton 2009
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Giant Planet Atmospheres and Spectra Calculate opacities Assume LTE, estimate line strength
terms: gi – statistical weight of ith energy level fij – oscillator strength of ij transition Fi, Fj – excitation energies Q(T) – partition function of species at T = Σgie-hcF/kT S – strength in cm2 s-1 species-1
Continued… Rayleigh scattering – most important in blue Albedo, phase angle
A little more complicated because light is reflected and emitted all in same part of spectrum
Fp/Fstar = Ag(Rp/a)2 ϕ(α) Last term is “phase function” – a combination of all the angles you can
think of Ag = geometric albedo, reflectivity
Derive a model light curve Θ= true anomaly of planet
11/24/09
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Last steps… Do the radiative transfer:
dI/dm = opacity x (I –S) Function of frequency and angle of propagation I = specific intensity, S = source function
W = dilution factor (Rstar/a)2
Spiegel et al. 2009
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Evolution of the luminosity of giant planets
Release of gravitational energy, release of internal energy (see eqn 7.13 in your book)
L = 4πR2 σ(Te4-T0
4) = -d(McvTi)/dt Te = actual effective temp. T0 = temperature in absence of internal sources (starlight) Ti = average internal temperature Simplifies to τ= Mcv/4L young planets are much more
luminous
Works well for Jupiter, not Saturn (additional heating from He settling?), not Uranus
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