37th DPS Meeting, 4-9 September 2005
Session 25 Planet and Satellite Formation
Oral, Tuesday, September 6, 2005, 2:00-3:50pm, Law LG19

[Previous] | [Session 25] | [Next]

[25.11] Constrants on the Orbital Evolution of Triton

M. Cuk, B. J. Gladman (Univ. British Columbia)

We (Cuk and Gladman 2005, ApJ 626, L113) present simulations of Triton's post-capture orbit that confirm the importance of Kozai-type oscillations in its orbital elements (Benner and McKinnon 1995). In the context of the tidal orbital evolution model (Goldreich et al. 1989), these variations require average pericenter distances much higher than previously published, and the timescale for the tidal orbital evolution of Triton becomes longer than the age of the Solar System.

Recently-discovered irregular satellites (Holman et al. 2004) present a new constraint on Triton's orbital history. Our numerical integrations of test particles indicate a timescale for Triton's orbital evolution to be less than 105 yrs for a reasonable number of distant satellites to survive Triton's passage. This timescale is wildly inconsistent with the exclusively tidal evolution (time scale of >108 yrs), but consistent with the gas-drag model which requires the presence of a primordial nebula (McKinnon and Leith 1995).

We suggest another source of drag that is available regardless of the capture epoch: debris from satellite-satellite collisions. Any major regular satellites will quickly collide among themselves after being perturbed by Triton (cf. Banfield and Murray 1992). The subsequent collisional debris disk would be prevented from re-accreting by Triton's perturbations and would eventually be swept up by Triton; given that the total mass of the Uranian satellite system is 40% of that of Triton, large scale evolution is possible. This scenario could have followed either collisional or the recently-discussed three-body-interaction-based capture (Agnor and Hamilton 2005).

[Previous] | [Session 25] | [Next]

Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.