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OSSOS measures the orbital fine structure of main-belt TNOs

Presentation #209.03 in the session TNO Theory/Formation and Observational Surveys (Oral Presentation)

Published onOct 23, 2023
OSSOS measures the orbital fine structure of main-belt TNOs

The Outer Solar System Origins Survey, when coupled with a few precursor surveys that share absolute calibration, has yielded the OSSOS++ sample of ≈1000 TNO orbits, allowing quantitative de-biasing of fine dynamical structure. The region between semimajor axes roughly 40 and 47 au is that of the main classical belt, whose objects make up a large fraction of the detections. Because the observations are well-characterized, abundant, and the orbits are high precision, one can detect previously unknown structure in the semimajor axis (a), perihelion (q) and inclination (i) distributions of the non-resonant classical belt objects. We show that: (1) there is fine detail that is visible with high-precision orbits that are converted to orbital elements which are both barycentric and converted to ‘free’ secular-corrected inclinations with respected to the a-dependent local Laplace pole. (2) there is a depletion, or ‘gap’ of a few tenths of an au in the semimajor axis distribution near a≈44.6 au, present over the entire inclination range. (3) The (a,q) structure is different on each side of the gap and inclination dependent. We interpret that the main-belt’s initial cold-classical population beyond the gap was altered into a ‘warm’ population with a wider inclination distribution. These structures are almost certainly due to dynamical processes at play near the end of planetary formation and migration.

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