core020.html

The 4¹/₂ Steps of the Core Accretion Model of Giant Planet Formation (cont) Step III: Oligarchic Growth (Kokubo & Ida; Thommes et al.; Goldreich et al.; Chambers)

Recall that as long as is not affected by M.
As the big guys grow, they have a larger fraction of system mass stir small guys.
- is roughly constant with mass, so .
So, growth slows and smaller oligarchs can catch up with larger ones.
Studies have shown that (Kokubo & Ida):
- The largest few objects at any given time are:
  1. of comparable mass
  2. orbital separation is ~10RH, (Earth at 10AU: RH=0.1AU)
    where RH is the gravitational sphere of influence and is f(M,a).
- So, as the system evolves:
  1. Number of big guys decreases.
  2. Their masses increase (mainly by eating planetesimals, but some mergers happen).
  3. Their separation increases.
Probably need a disk massive enough so that the cores grow to ~10 M_E in this mode (Lissauer).