Neptune’s resonances in the Scattered Disk. (arXiv:1901.06040v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lan_L/0/1/0/all/0/1">Lei Lan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Malhotra_R/0/1/0/all/0/1">Renu Malhotra</a>
The Scattered Disk Objects (SDOs) are thought to be a small fraction of the
ancient population of leftover planetesimals in the outer solar system that
were gravitationally scattered by the giant planets and have managed to survive
primarily by capture and sticking in Neptune’s exterior mean motion resonances
(MMRs). In order to advance understanding of the role of MMRs in the dynamics
of the SDOs, we investigate the phase space structure of a large number of
Neptune’s MMRs in the semi-major axis range 33–140~au by use of Poincar’e
sections of the circular planar restricted three body model for the full range
of particle eccentricity pertinent to SDOs. We find that, for eccentricities
corresponding to perihelion distances near Neptune’s orbit, distant MMRs have
stable widths that are surprisingly large and of similar size to those of the
closer-in MMRs. We identify a phase-shifted second resonance zone that exists
in the phase space at planet-crossing eccentricities but not at lower
eccentricities; this second resonance zone plays an important role in the
dynamics of SDOs in lengthening their dynamical lifetimes. Our non-perturbative
measurements of the sizes of the stable resonance zones provide an explanation
for the prominence of the $N$:1 sequence of MMRs over the $N$:2, $N$:3
sequences and other MMRs in the population statistics of SDOs, yield a
theoretical understanding of the outer boundary of SDOs at perihelion distance
near 36~au, and also provide a tool to more easily identify resonant objects.
The Scattered Disk Objects (SDOs) are thought to be a small fraction of the
ancient population of leftover planetesimals in the outer solar system that
were gravitationally scattered by the giant planets and have managed to survive
primarily by capture and sticking in Neptune’s exterior mean motion resonances
(MMRs). In order to advance understanding of the role of MMRs in the dynamics
of the SDOs, we investigate the phase space structure of a large number of
Neptune’s MMRs in the semi-major axis range 33–140~au by use of Poincar’e
sections of the circular planar restricted three body model for the full range
of particle eccentricity pertinent to SDOs. We find that, for eccentricities
corresponding to perihelion distances near Neptune’s orbit, distant MMRs have
stable widths that are surprisingly large and of similar size to those of the
closer-in MMRs. We identify a phase-shifted second resonance zone that exists
in the phase space at planet-crossing eccentricities but not at lower
eccentricities; this second resonance zone plays an important role in the
dynamics of SDOs in lengthening their dynamical lifetimes. Our non-perturbative
measurements of the sizes of the stable resonance zones provide an explanation
for the prominence of the $N$:1 sequence of MMRs over the $N$:2, $N$:3
sequences and other MMRs in the population statistics of SDOs, yield a
theoretical understanding of the outer boundary of SDOs at perihelion distance
near 36~au, and also provide a tool to more easily identify resonant objects.
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