Dynamical evolution of a self-gravitating planetesimal disk in the distant trans-Neptunian region

Abstract

Aims. We study the dynamical evolution of a system consisting of the giant planets and a massive planetesimal disk over the age of the Solar System. The main question addressed in this study is whether distant trans-Neptunian objects could have come about as a result of the combined action of planetary perturbations and the self-gravity of the disk. Methods. We carried out a series of full N-body numerical simulations of gravitational interactions between the giant planets and a massive outer disk of planetesimals. Results. Our simulations show that the collective gravity of the giant planets and massive planetesimals produces distant trans-Neptunian objects across a wide range of the initial disk mass. The majority of objects that survive up through the age of the Solar System have perihelion distances of q > 40 au. In this region, there is a tendency toward a slow decrease in eccentricities and an increase in perihelion distances for objects with semimajor axes a > 150 au. Secular resonances between distant planetesimals play a major role in increasing their perihelion distances. This explains the origin of Sedna-type objects. In our integrations for the age of the Solar System, we registered times with both high and low clustering of longitudes of perihelion and arguments of perihelion for objects with q > 40 au, a > 150 au. The resulting distribution of inclinations in our model and the observed distribution of inclinations for distant trans-Neptunian objects have similar average values of around 20°. Conclusions. Distant trans-Neptunian objects are a natural consequence in the models that include migrating giant planets and a self-gravitating planetesimal disk.