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Col-OSSOS: The Distribution of Surface Classes in Neptune’s Resonances

Presentation #105.08 in the session Physical Properties of Centaurs & KBOs.

Published onOct 20, 2022
Col-OSSOS: The Distribution of Surface Classes in Neptune’s Resonances

The distribution of surface classes of resonant trans-Neptunian objects (TNOs) provides constraints on the proto-planetesimal disk and giant planet migration. To better understand the surfaces of TNOs, the Colours of the Outer Solar System Origins Survey (Col-OSSOS) acquired multi-band photometry of 92 TNOs, and found that the surfaces of TNOs can be well described by two surface classifications, BrightIR and FaintIR. These classifications both include optically red members and are differentiated predominantly based on whether their near-infrared spectral slope is similar to their optical spectral slope. The vast majority of cold classical TNOs, with dynamically unexcited orbits, have the FaintIR surface classification, and we infer that TNOs in other dynamical classifications with FaintIR surfaces share a common origin with the cold classical TNOs. Comparison between the resonant populations and the possible parent populations of cold classical and dynamically excited TNOs reveal that the 3:2 has minimal contributions from the FaintIR class, consistent with the ν8 secular resonance clearing the region near the 3:2 before any sweeping capture occurred. Conversely, the FaintIR class is over-represented in the 4:3 resonance, 2:1 resonance, and the resonances within the cold classical belt, implying that the FaintIR surface formed in the protoplanetary disk between ≲34.6 au to ≲47 au, though the outer bound depends on the degree of resonance sweeping during migration. The presence and absence of the FaintIR surfaces in Neptune’s resonances provides critical constraints for the history of Neptune’s migration, the evolution of the ν8, and the surface class distribution in the initial planetesimal disk.

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