So, what am I talking about?
Between ~4 and ~10AU:
- 1-10km objects form by two-body accretion or gravitational instability.
- Big guys grow faster than small guys run away.
- Theory predict we should end up with 4 cores (which are like
Uranus and Neptune).
- Largest core(s) start to accrete gas from solar nebula.
- Remaining cores gravitationally scattered by growing gas giants.
- Their orbits circularized by trans-planetary disk.