- Come from the scattered disk. (Duncan & Levison 1997)
- The Kuiper belt is simply not populous enough.
- Traditionally thought to come from the classical Oort cloud. (Duncan, Quinn, & Tremaine 1987)
- But, this does not reproduce the inclination distribution.
- Levison et al. (2006) argues that they come from the outer edge of the scattered disk.
- Objects' semi-major axes random walk because of planets.
- When they get to ~104AU, Galactic tides become important.
- Some will have their perihelia lifted Oort cloud.
- However, others will have their perihelia driven in HTCs.
- This reproduces observed orbit distribution.
- Traditionally thought to come from the classical Oort cloud......
Probably mainly true.
- However, the Levison et al. (2006) mechanism also produces LPCs with a > 30,000 AU.
- The Sedna population could also be contributing. (cf. Kaib & Quinn 2010)
- Using the Levison et al. (2006) mechanism.