Institute for Advanced Study Informal Astrophysics Seminar

In a planetary system with well-spaced planets, there is a nonlinear instability that can lead to chaotic behaviour. One of the planets may gradually become unstable, in which case its orbit can become highly eccentric and/or inclined. If an unstable planet comes close to the star, its orbit will be circularized by tides. This can explain the numerous Jupiter-mass planets that have been discovered to orbit very close to the central star (`hot Jupiters'). After an unstable planet escapes the influence of the other planets, the remaining planetary system becomes increasingly stable. This may explain the stable architecture of observed systems.