High-order mean-motion resonances in the main belt

Belgrade Astronomical Observatory, 11000, Volgina 7, Belgrade, Serbia

^★ Corresponding author: smirik@gmail.com

Received: 24 September 2025
Accepted: 16 October 2025

Abstract

Aims. In this paper, we present statistical research on a representative sample of asteroids captured in low- to high-order (resonant order q ≤ 100) two-body and three-body (q ≤ 10) mean motion resonances (MMRs) in the main belt to assess the fraction of resonant asteroids.

Methods. We took orbital elements from the Minor Planet Center database and NASA JPL. For this research we used the open-source package resonances for (1) numerical integrations of orbits for asteroids over 100000 years with planetary perturbations and (2) resonance identification. We identified all objects captured in two-body and three-body MMRs, as well as those captured in more than one resonance.

Results. The study reveals that 53.76% of asteroids in the studied sample are resonant. The subset of two-body resonances contains 40.07% resonant asteroids, while the three-body subset contains 23.72% resonant asteroids. The number of asteroids trapped in two-body MMRs is significantly higher (40.07% vs. 2.0-5.0%) than previously known because of the inclusion of high-order mean motion resonances. The highest amount of two-body resonant asteroids is found at order ≈ 36. Additionally, our results indicate that 25.57% of asteroids are involved in multiple MMRs, either through simultaneous trapping or through the phenomenon of resonance sticking, migrating from one resonance to another.

Conclusions. We conclude that resonances whose order is close to the mean of all those analyzed here trap the largest number of asteroids, and that about half of the analyzed main belt asteroids are resonant. Moreover, roughly one quarter of resonant asteroids undergo migration from one MMR to another. Taken together, these results highlight the significant role of MMRs in shaping asteroid dynamics.