31 research outputs found
Constraints on the Orbital Evolution of Triton
We present simulations of Triton's post-capture orbit that confirm the
importance of Kozai-type oscillations in its orbital elements. In the context
of the tidal orbital evolution model, 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 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 yrs
for a reasonable number of distant satellites to survive Triton's passage. This
timescale is inconsistent with the exclusively tidal evolution (time scale of
yrs), but consistent with the interestion with the debris from
satellite-satellite collisions. Any major regular satellites will quickly
collide among themselves after being perturbed by Triton, and the resulting
debris disk 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.Comment: 10 pages, 4 figures, accepted for ApJ
The energy budget and figure of Earth during recovery from the Moon-forming giant impact
Quantifying the energy budget of Earth in the first few million years following the Moon-forming giant impact is vital to understanding Earth's initial thermal state and the dynamics of lunar tidal evolution. After the impact, the body was substantially vaporized and rotating rapidly, very different from the planet we know today. The subsequent evolution of Earth's energy budget, as the body cooled and angular momentum was transferred during lunar tidal recession, has not been accurately calculated with all relevant energy components included. Here, we use giant impact simulations and planetary structure models to calculate the energy budget at stages in Earth's evolution. We show that the figure and internal structure of Earth changed substantially during its post-impact evolution and that changes in kinetic, potential, and internal energy were all significant. These changes have important implications for the dynamics of tidal recession and the thermal structure of early Earth