Trojan Asteroids (Morbidelli et al. 2005)
So, can it also explain the other primitive bodies?
- Observational Constraint:
- Trojans are dynamically excited - filling phase space (Levison et al.)
- Previous models of Trojan formation say they formed when gas was still around.
- They usually invoke Jupiter's growth (Marzari & Scholl; Feming & Hamilton)
and/or gas drag (Peale).
- However, gas damps inclinations, so how did the Trojans get so excited?
- The Nice Model solves this problem:
- Gomes showed that the Trojans are unstable if Jupiter and Saturn crossed the 1:2 MMR.
- However, instability implies that the tapole region of phase space becomes connected with the outside
things can get in.
- We integrated the orbits millions of particles that had orbits consistent with migration.
- The orbits of the resulting Trojans match observations fairly well.
- Predicts 3x10-5 Earth-mass of Trojans.
- Recent observations (Sloan DSS) says ~10-5 Earth-mass.
- Recently discovered binary Trojan, (617) Patroclus, has a density of 1.0 g/cm3
more like comets and KBOs than asteroids.