  Mean motion resonances [MMRs] play an important role in the formation and
evolution of planetary systems and have significantly influenced the orbital
properties and distribution of planets and minor planets in the solar system as
well as exo-planetary systems. Most previous theoretical analyses have focused
on the low-to-moderate eccentricity regime, but with new discoveries of high
eccentricity resonant minor planets and even exoplanets, there is increasing
motivation to examine MMRs in the high eccentricity regime. Here we report on a
study of the high eccentricity regime of MMRs in the circular planar restricted
three-body problem. Non-perturbative numerical analyses of the 2:1 and the 3:2
interior resonances are carried out for a wide range of secondary-to-primary
mass ratio, and for a wide range of eccentricity of the test particle. The
surface-of-section technique is used to study the phase space structure near
resonances. We identify transitions in phase space at certain critical
eccentricities related to the geometry of resonant orbits; new stable libration
zones appear at high eccentricity at libration centers shifted from those at
low eccentricities. We present novel results on the mass and eccentricity
dependence of the resonance libration centers and their widths in semi-major
axis. Our results show that MMRs have sizable libration zones at high
eccentricities, comparable to those at lower eccentricities.
