What other “planetary formation mechanisms” exist beyond “gravitational collapse”? My curiosity was pricked by the an edit made to this post: What&#39;s the distinction between &quot;planetary formation mechanisms&quot; and &quot;gravitational collapse&quot;? sadly the edit was changing the original questions intend, so I had to roll it back.

But the question of the edit itself felt interesting to me aswell, so I'm reposting it here in another question:

What "planetary formation mechanisms" other than "gravitational collapse" exist?
"Gravitational collapse" is not the generally used name of any planet formation model. Gravitational disk instability may be what is meant.

In the context of the answer you refer to, the other, and probably dominant planet formation is known as the core accretion model.

Of course gravity plays a crucial role here too, but the distinction between this and direct collapse of an instability in a gas disc (what is perhaps being referred to as gravitational collapse) is that the major phase of gas accretion takes place after the initial formation of a rocky/icy core. This may account for the correlation between planet frequency and host star metallicity.