The formation of extra-solar planet systems can be achieved in two ways.
- Supporting details
1) In the first, a terrestrial mass planet can form in the inner disk, while gas giant forms beyond the snow line. During the inward migration of the gas giant the terrestrial planet is captured in a mean motion resonance where it remains until migration ceases.
2) In the second, a gas giant migrates through a disk of planetismals. This results in mean motion resonances with the gas giant sweeping through the disk of planetismals, causing material to be either scattered out of the system or captured into these resonances.
Any captured material wll coagulate into a terrestrial planet, provided the density is sufficiently high.