Possible origin of Mars-crossing asteroids and related dynamical properties of inner main-belt asteroids

¹ National Key Laboratory of Science and Technology on Aerospace Flight Dynamics, 100094 Beijing, China
² Beijing Aerospace Control Center, 100094 Beijing, China
³ Shandong University of Science and Technology, 266590 Qingdao, China
⁴ Chinese Academy of Surveying and Mapping, 100036 Beijing, China
⁵ Nanjing University, 210023 Nanjing, China
⁶ Wuhan University, 430079 Wuhan, China
⁷ Bejing Normal University, 100875 Beijing, China

^★ Corresponding authors; shanhongliu@whu.edu.cn, hanyl@sdust.edu.cn

Received: 18 June 2024
Accepted: 14 October 2024

Abstract

Context. The orbital element distribution of the inner main belt (IMB) provides clues to the origin of the main-belt asteroids. Mars-crossing asteroids (MCAs) and near-Earth objects (NEOs) can provide some references to validate and improve theoretical models of the IMB evolution.

Aims. With the updated Asteroid Families Portal database, we analyzed the distribution of orbital elements and the dynamic completeness limit of IMB asteroids. By incorporating larger and more diverse datasets, the study seeks to provide a more comprehensive understanding of the IMB and MCAs origin and evolution.

Methods. We fitted the completeness-limit magnitude for the IMB. The size frequency and albedo distribution were used to analyze the family characteristics. The role of chaotic effects in the dynamic evolution of IMB and MCAs is further quantified by simulations.

Results. An albedo analysis showed that some halo asteroids may have originated from family asteroids, whereas the remaining non-family asteroids (14%) are likely to be members of a potential ghost family. We estimated the chaotic diffusion of asteroid orbits considering 1M/2A mean motion resonance. The eccentricity diffusion rate is estimated to be 0.45 and the inclination diffusion rate is 0.4 for resonant asteroids. The loss rate of MCAs I_IMC(17.6) = 24.13 Myr⁻¹, while the loss rate of the IMB asteroids due to the chaotic diffusion is 0.2648 Myr⁻¹, which represents only 1.1% of MCAs. This indicates that chaotic diffusion has a limited capacity to replenish MCAs. However, for the large MCAs, a loss rate of I_IMC(12) = 0.2646 Myr⁻¹ was observed. This suggests that the large MCAs (H < 12) are in the dynamic equilibrium, primarily evolving through chaotic diffusion.