OSSOS. XVIII. Constraining Migration Models with the 2:1 Resonance Using the Outer Solar System Origins Survey

Abstract

Resonant dynamics plays a significant role in the past evolution and current state of our outer Solar System. The population ratios and spatial distribution of Neptune's resonant populations are direct clues to understanding the history of our planetary system. The orbital structure of the objects in Neptune's 2:1 mean-motion resonance (twotinos) has the potential to be a tracer of planetary migration processes. Different migration processes produce distinct architectures, recognizable by well-characterized surveys. However, previous characterized surveys only discovered a few twotinos, making it impossible to model the intrinsic twotino population.With a well-designed cadence and nearly 100% tracking success, the Outer Solar System Origins Survey (OSSOS) discovered 838 trans-Neptunian objects, of which 34 are securely twotinos with well-constrained libration angles and amplitudes. We use the OSSOS twotinos and the survey characterization parameters via the OSSOS Survey Simulator to inspect the intrinsic population and orbital distributions of twotino. The estimated twotino population, 4400 +1500 −1100 with H r < 8.66 (diameter∼100km) at 95% confidence, is consistent with the previous low-precision estimate. We also constrain the width of the inclination distribution to a relatively narrow value of σ i =6 •+1 −1 , and find the eccentricity distribution is consistent with a Gaussian centered on e c = 0.275 with a width e w = 0.06. We find a single-slope exponential luminosity function with α = 0.6 for the twotinos. Finally, we for the first time meaningfully constrain 2 Chen et al.the fraction of symmetric twotinos, and the ratio of the leading asymmetric islands; both fractions are in a range of 0.2-0.6. These measurements rule out certain theoretical models of Neptune's migration history.

OSSOS XX: The Meaning of Kuiper Belt Colors

“…Another consequence of the capture of low-i objects into the 2:1 resonance is that the inclination distribution of plutinos should be narrower than that of the 3:2 or 5:2 resonant populations. And this is indeed supported by observations (e.g., Chen et al 2019).…”

“…There are also tracked detections in the inner 4:3 resonance, the CKB resonances (e.g., 5:3, 7:4, 8:5), and the outer 5:2 resonance. An interesting difference between the OSSOS and model distributions is noted for the 2:1 and 5:2 resonances, where OSSOS detected important "core" populations ( Figures 5(a) and (b); Volk et al 2016;Chen et al 2019). These populations are present in the raw results ( Figure 3) but are not sufficiently large to stand out in model detections (Figures 5(c) and (d)).…”

GLISSE: A GPU-optimized planetary system integrator with application to orbital stability calculations

“…The two asymmetric islands are equally populated. The symmetric librators have an upper e envelope at each libration amplitude, again similar to the 2:1 [28].…”

“…Many other transneptunian objects (TNOs) also reside in the 3:2, and as such the structure of this resonance has been heavily studied analytically and numerically [23,26]. Other resonances with reasonable exploration of the long-term stability of most of the resonant phase space include the 2:1 [27,28] and the 5:2 [29]. The 3:1 resonance has no similarly rigorous exploration.…”

“…We observed no cases of libration with φ 31 centered on zero. Although some particles librate around other angles, the amplitude of libration is low and so the criterion that we use will still correctly identify such particles as librating; in particular, for the 3:1 there are asymmetric librators which librate around φ 31 70 • or290 • , like for the 2:1 [22,28], that are correctly diagnosed due to φ avoiding zero.…”