Core Accretion, Model for Giant Planet Formation

Definition

Core accretion is the standard model for giant planet formation. The core accretion model proposes that the formation of giant planets starts with core formation followed by gas accretion. First, small bodies continually collide to form larger ones, eventually reaching the stage of protoplanetary cores, which are essentially large planetary embryos that form in the giant planet region. Cores that reach masses of a few Earth masses begin to accrete gas from the protoplanetary disk, slowly at first, and then at a runaway rate when the gaseous envelope’s mass becomes comparable to the core mass. Cores, therefore, represent the “seeds” of gas giant and ice giant planets in this model. An alternative model for giant planet formation is disk instability that proposes that giant planets form via a local gravitational collapse in the disk, which can later be followed by core formation and accretion of solids.

See Also

• Atmosphere, Primitive Envelope

• Giant Planets

• Planet Formation...