A new inclination instability reshapes Keplerian disks into cones: application to the outer Solar System

Understand

Disks of bodies orbiting a much more massive central object are extremely common in astrophysics.

• When the orbits comprising such disks are eccentric, we show they are susceptible to a new dynamical instability.
• Gravitational forces between bodies in the disk drive exponential growth of their orbital inclinations and clustering in their angles of pericenter, expanding an initially thin disk into a conical shape by giving each orbit an identical 'tilt' with respect to the disk plane.
• This new instability dynamically produces the unusual distribution of orbits observed for minor planets beyond Neptune, suggesting that the instability has shaped the outer Solar System.