The Resonant Trans-Neptunian Populations

Abstract

The trans-Neptunian objects (TNOs) trapped in mean-motion resonances with Neptune were likely emplaced there during planet migration late in the giant-planet formation process. We perform detailed modeling of the resonant objects detected in the Canada-France Ecliptic Plane Survey (CFEPS) in order to provide population estimates and, for some resonances, constrain the complex internal orbital element distribution. Detection biases play a critical role because phase relationships with Neptune make object discovery more likely at certain longitudes. This paper discusses the 3:2, 5:2, 2:1, 3:1, 5:1, 4:3, 5:3, 7:3, 5:4, and 7:4 mean-motion resonances, all of which had CFEPS detections, along with our upper limit on 1:1 Neptune Trojans (which is consistent with their small population estimated elsewhere). For the Plutinos (TNOs in the 3:2 resonance) we refine the orbital element distribution given in Kavelaars et al. (2009) and show that steep H-magnitude distributions (N (H ) ∝ 10 αH , with α = 0.8-0.9) are favored in the range H g = 8-9, and confirm that this resonance does not share the inclination distribution of the classical Kuiper Belt. We give the first population estimate for the 5:2 resonance and find that, to within the uncertainties, the population is equal to that of the 3:2 ( 13,000 TNOs with H g < 9.16), whereas the 2:1 population is smaller by a factor of 3-4 compared to the other two resonances. We also measure significant populations inhabiting the 4:3, 5:3, 7:3, 5:4, 7:4, 3:1, and 5:1 resonances, with H g < 9.16 (D > 100 km) populations in the thousands. We compare our intrinsic population and orbital element distributions with several published models of resonant-TNO production; the most striking discrepancy is that resonances beyond the 2:1 are in reality more heavily populated than in published models.

OSSOS. VII. 800+ Trans-Neptunian Objects—The Complete Data Release

“…The blocks were placed to avoid the dense star fields of the galaxy (schematically indicated by gray shading). Gray dots show the predicted position density of the observable fraction (m r < 24.7) of objects in the 3:2 resonance with Neptune, as modeled by Gladman et al (2012). Blue dots are the 840 characterized OSSOS discoveries (Table 3), which were found at heliocentric distances between 6 and 83au.…”

“…As an example, considering the 2:1 mean-motion resonance with Neptune, rapid planetary migration results in fewer objects librating around f ∼ 90°than about the other asymmetric island near f ∼ 270°, with the fraction depending on the pace and duration of Neptune's early wandering through the solar system (Murray-Clay & Chiang 2005). The population ratios between particular resonances differ if Neptune's orbital evolution is modeled as a smooth migration (Chiang et al 2003;Hahn & Malhotra 2005) or as scattered and damped (Levison et al 2008), e.g., between the 2:1, 3:2, and 5:2 resonances (Gladman et al 2012). Three possible mechanisms for resonant capture-large-scale migration of Neptune (e.g., Malhotra 1995;Hahn & Malhotra 2005), chaotic capture of scattered objects (Levison et al 2008), and capture of scattered objects through fast secular evolution (Dawson & Murray-Clay 2012)-may also result in different libration amplitudes and resonance occupation ratios.…”

Statistics of encounters in the trans-Neptunian region

“…In most cases observational and selection biases were present. The Canadian-France Ecliptic Plane Survey (CFEPS) was set up at the beginning of the past decade (Kavelaars et al 2009;Petit et al 2011;Gladman et al 2012), developing a discovery and follow-up strategy intended to minimize observational biases and to obtain a population of objects that can be considered representative of all dynamical classes of the trans-Neptunian region (also known as the Edgeworth-Kuiper belt, EKB). As a result of this observational effort involving researchers and facilities in many countries, we begin to understand the overall structure of the trans-Neptunian objects (TNO) populations in terms of dynamical features and absolute magnitude number distributions.…”

Ossos. Iv. Discovery of a Dwarf Planet Candidate in the 9:2 Resonance With Neptune

“…The resonant protection provided by the 9:2 resonance is very similar to that provided by the 3:2 and 5:2 mean-motion resonances (Cohen & Hubbard 1965;Gladman et al 2012). .…”