DDA 2015 – Implications of Resonant and Near-Resonant Planetary Systems for Planet Formation

This is one of a series of notes taken during the 2015 meeting of the AAS Division on Dynamical Astronomy, 3-7 May, at CalTech. An index to this series (all the papers presented at the meeting) is here.

Eric Ford (Penn State)


Observations of strongly interacting planetary systems in or near a mean motion resonance are unusually sensitive to planet masses and orbital properties, including dynamical properties that can help illuminate planet formation. Having developed a powerful toolbox for translating Doppler and/or transit timing observations into physics parameters, now we are able to characterize the resonant and secular behaviour of several strongly interacting planetary systems. I will present recent results for selected resonant and near-resonant planetary systems and discuss implications for planet formation. In particular, I will address implications for the nature and extent of orbital migration for giant and low-mass planets.


  • How didSTIPs form?
    • Three strawman models:
      • In situ formation: wrong
      • Large-scale disk formation: wrong
      • Nearly in situ formation plus modest early radial drift
  • STIP examples:
    • GJ 876: 4 planets
  • 55 Cnc: 5 planets, MMR
  • … Meh.

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