Migration and Resonance Crossing (Tsiganis et al.)

• We found that we can solve this problem if Jupiter and Saturn crossed 1:2 MMR.
  
  
• Thus, we believe that the migration proceeded as follows:
  1. System is initially compact with Saturn inside of 1:2 MMR and a massive disk beyond planets.
     
  2. Jupiter and Saturn diverge until they hit the 1:2 MMR.
     
  3. The resonance excites the eccentricity of both Jupiter and Saturn
     Uranus and Neptune go unstable.
     
  4. Uranus and/or Neptune scatter off of Saturn, keeping its eccentricity large.
     
  5. Uranus and Neptune settle to current orbits due to dynamical friction with the disk.
  
  
• This process reproduces the orbital elements of the giant planets fairly well.
  • We put an edge to the disk near 30AU, which determines Neptune's location.
    • I will justify this in the Kuiper belt section.
  • Results are only sensitive to one free parameter - disk mass.
    • Needs a disk of about 35M_E.

So this works, but is there any observational evidence that it happened?