Page "Protoplanetary disk" Paragraph 7

The nebular hypothesis of solar system formation describes how protoplanetary disks are thought to evolve into planetary systems.

Electrostatic and gravitational interactions may cause the dust and ice grains in the disk to accrete into planetesimals.

This process competes against the stellar wind, which drives the gas out of the system, and accretion, which pulls material into the central T Tauri star.