Joint Astrophysics Colloquium

Multi-planetary systems, Saturn's Rings and the new collisional N-body code REBOUND

Hanno Rein

IAS Princeton

The increasing number of discovered extra-solar planets opens a new opportunity for studying the formation of planetary systems. Resonant systems are of particular interest because their dynamical configuration provides very strong constraints on the otherwise unobservable phase of formation and migration. I will illustrate the main effects of planetary migration in multi-planetary systems by discussing several examples from past and ongoing studies.

By observing a specific resonance in a planetary system, one can constrain the properties of the proto-planetary disc. Close, first order resonances require a fast migration speed for capture, which can be attributed to a massive disc. Furthermore, proto-planets are exposed to stochastic forces, generated by density fluctuations in the proto-planetary disc. Systems with massive planets are usually stable. However, systems with smaller planets such as Super-Earths, similar to those that have been discovered by the Kepler spacecraft, can get easily disrupted.

Interestingly, these systems are dynamically very similar to Saturn's rings. The stochastic migration of small bodies in Saturn's rings can be described using the same equations. I will show new results from our current work with direct N-body simulations which aim to be directly comparable to the observations of moonlets that show signs of non-Keplerian motion.

In the last part of the talk will be devoted to advertising a new freely available collisional N-body code, REBOUND. All of the numerical work presented in this talk has been performed with REBOUND. I will show how you can easily reproduce these calculations yourself.