Secular Resonances in the Inner Solar System
P. Michel (Obs. Côte d'Azur)
Many studies have shown that secular resonances are very effective
to transport asteroids from the main belt to the planetary-crossing
region. Recently, a semianalytical study based on the expansion of
the Hamiltonian of the N-body problem with respect to planetary
orbital eccentricities and inclinations has allowed to obtain the
first location of the linear secular resonances in the inner Solar
System (semimajor axes smaller than 2 AU), i.e. where many Near-Earth
Asteroids (NEAs) evolve. The results show that all these resonances, as
well as the Kozai one, are present and that some can even overlap.
Moreover, a resonant model has been derived for each resonance in order
to study their effect. It appears that the secular resonances involving
inner planets' orbital frequencies (i) can cause great variations of
eccentricities and inclinations, (ii) provide a transport mechanism
from the Mars-crossing region to the Earth-crossing one and (iii)
can lead NEAs to highly-inclined orbits. Moreover, the overlapping
of two resonances can lead to large scale chaos. The
dynamics of NEAs can thus be affected by several mechanisms and
therefore, secular
resonances must be taken into account to study their evolutions since
they could partly explain the observed orbital distributions and lifetimes
of these objects.