Kimmo A. Innanen

The Stability of Quasi Satellites in the Outer Solar System

Quasi satellites are bodies in a particular configuration of a 1 : 1 mean motion resonance, one in which they librate about the longitude of their associated planet. We investigate numerically the stability of such orbits around the giant planets of our solar system. We find that test particles can remain on quasi-satellite orbits around Uranus and Neptune for times up to 109 yr in some cases, though only at low inclinations relative to their accompanying planet and over a restricted range of heliocentric eccentricities. These stable areas are well outside the traditional satellite region. Based on these results, we conclude that a primordial population of such objects may still exist in our solar system.

Earth Trojan Asteroids: A Study in Support of Observational Searches

Abstract Observational searches for asteroids orbiting near Earths triangular Lagrange points face unique obstacles. A population of such asteroids would occupy a large projected area on the sky (possibly hundreds of square degrees) and is not favorably placed with respect to the Sun. Here we examine the properties of synthetic populations of Earth “Trojans” in order to aid in the optimization of observational searches for them. We find that the highest on-sky projected number densities are not located at the positions of the L 4 and L 5 points themselves, but rather a few degrees closer to the Sun. Also, asteroids on orbits about the L 4 and L 5 points typically brighten as the difference between their ecliptic longitude and that of the Sun increases owing to phase effects, but their number density on the sky concurrently falls rapidly.