The Dynamics of Centaurs in the Vicinity of the 2:1 Mean Motion Resonance of Neptune and Uranus Trojan Region

In this work we present the results of a suite of dynamical simulations following the orbital evolution of 8,022 hypothetical Centaur objects. These Centaurs begin our integrations on orbits in the vicinity of the 2:1 mean motion resonance with Neptune, and we follow their dynamical evolution for a period of 3 Myr under the gravitational influence of a motionless Sun and the four Jovian planets. The great majority of the test particles studied rapidly escaped from the vicinity of the 2:1 mean motion resonance of Neptune and diffused throughout the Solar System. The average libration time of Centaurs in the vicinity of 2:1 mean motion resonance of Neptune was found to be just 27 kyr. Although two particles did remain near the resonance for more than 1 Myr. Upon leaving the vicinity of the 2:1 resonance, the majority of test particles evolved by a process of random walk in semi-major axis, due to repeated close encounters with the giant planets.Comment: 14 page

Are Two of the Neptune Trojans Dynamically Unstable?

The Neptune Trojans are the most recently discovered population of small bodies in the Solar System. To date, only eight have been discovered, though it is thought likely that the total population at least rivals that of the asteroid belt. Their origin is still the subject of some debate. Here, we detail the results of dynamical studies of two Neptune Trojans, 2001 QR322 and 2008 LC18. We find that both objects lie very close to boundaries between dynamically stable and unstable regions, with a significant probability that either or both of the objects are actually unstable on timescales of a few hundred million years. Such instability supports the idea that at least these two Neptune Trojans are dynamically captured objects, rather than objects that formed in situ. This that does not, however, rule out the possibility that these two objects were captured during Neptune's proposed post-formation migration, and have remained as Trojans ever since.Comment: 13 pages, 4 figures, 3 tables, Accepted to appear in the peer-reviewed proceedings of the 11th annual Australian Space Science Conferenc

Observations of the D/H ratio in Methane in the atmosphere of Saturn's moon, Titan - where did the Saturnian system form?

The details of the Solar system's formation are still heavily debated. Questions remain about the formation locations of the giant planets, and the degree to which volatile material was mixed throughout the proto-planetary system. One diagnostic which offers great promise in helping to unravel the history of planet formation is the study of the level of deuteration in various Solar system bodies. For example, the D/H ratio of methane in the atmosphere of Titan can be used as a diagnostic of the initial conditions of the solar nebula within the region of giant planet formation, and can help us to determine where Titan (and, by extension, the Saturnian system) accreted its volatile material. The level of Titanian deuteration also has implications for both the sources and long term evolution of Titan's atmospheric composition. We present the results of observations taken in the 1.58 microns window using the NIFS spectrometer on the Gemini telescope, and model our data using the VSTAR line--by--line transfer model, which yields a D/H ratio for Titan's atmosphere of 143+/-16) x 10^{-6} [1]. We are currently in the process of modeling the Gemini high resolution GNIRS spectra using new sets of line parameters derived for methane in the region between 1.2-1.7 microns [2].Comment: 12 pages, 4 figures, Accepted for publication in proceedings of the Australian Space Science Conference 201