Local: Auditório do CEM
A Classification of NEAs through their Dynamical Evolution
Dr. Othon Winter (GDOP)
The orbits of the Near-Earth Asteroids (NEAs) are usually classified as Atens, Apollo, Amor and Atira. This classification is based on the current semi-major axis (a) and eccentricity (e) of the asteroid’s orbit. However, the orbital evolution of the NEAs is dominated by gravitational interaction with the terrestrial planets, in such a way that a single planetary close encounter can move an asteroid from an initial group to another one. In this work we present an alternative to the current classification of the NEAs by taking into account their temporal evolution on the a x e space. The approach is based on numerical integrations of the gravitational N-body problem for a system composed by the Sun, the planets Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune and a sample of 1500 NEAs, for a time span of 10 Myr. Then, we characterised and quantified the transitions of the orbits of these asteroids among the groups Atens, Apollo, Amor and Atira, along their lifetime. This analysis confirmed that, in fact, the transitions of the NEAs between the groups are very common. However, we found that a significant fraction of NEAs dynamically evolves in the a x e space under predominant patterns, regardless of their initial classification. Such behavior poses a dynamically based classification for the NEAs, composed by at least three distinct groups: those under resonance effects, the guided ones, and the confined ones.