  Mean motion resonances are important in the analysis and understanding of the
dynamics of planetary systems. While perturbative approaches have been dominant
in many previous studies, recent non-perturbative approaches have revealed
novel properties in the low eccentricity regime for interior mean motion
resonances of Jupiter in the fundamental model of the circular planar
restricted three body model. Here we extend the non-perturbative investigation
to exterior mean motion resonances in the low eccentricity regime (up to about
0.1) and for perturber mass in the range 5e-5 to 1e-3 (in units of the central
mass). Our results demonstrate that first order exterior resonances have two
branches at low eccentricity as well as low-eccentricity bridges connecting
neighboring first order resonances. With increasing perturber mass, higher
order resonances dissolve into chaos whereas low order resonances persist with
larger widths in their radial extent but smaller azimuthal widths. For low
order resonances, we also detect secondary resonances arising from small
integer commensurabilities between resonant librations and the synodic
frequency. These secondary resonances contribute significantly to generating
the chaotic sea that typically occurs near mean motion resonances of
higher-mass perturbers.
