The Good – Trojan Asteroids (Morbidelli et al. 2005)
Neptune Trojans: There is 6 known Trojans of Neptune.
- A review: There are ~160,000 asteroids with r>1km in Jupiter's Lagrange points.
- They 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?
- Back to the Nice Model:
- 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 consistant with migration.
- 1 out of 1x106 were trapped in Trojans orbits.
- The orbits of the resulting Trojans match observations fairly well.
- A 35 Earth-mass trans-Neptunian disk
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 0.8 g/cm3
more like comets and KBOs than asteroids.
- We naturally make these objects during our full N-body simulations of migration.