Theory 32/Competing Rates/Planet formation
Planetesimals Balance Growth and Loss
The claim
Whether a planetesimal grows into a planet is set by the ratio of accretion to collisional erosion in its feeding zone.
01Mechanism
Growth requires accretion to outpace disruption; the balance shifts with relative velocities, which are set by the local disc.
02Prediction
Final masses should track the ratio.
03Refutation
Growth tracking accretion alone would remove erosion.