Transit of asteroids across the 7/3 Kirkwood gap under the Yarkovsky effect

¹ School of Astronomy and Space Science, Nanjing University, 163 Xianlin Avenue, Nanjing 210046, PR China
e-mail: zhouly@nju.edu.cn
² Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing, PR China
³ Institute of Space Astronomy and Extraterrestrial Exploration (NJU & CAST), Nanjing University, Nanjing, PR China
⁴ Institute of Astronomy, National Central University, Jhongli, Taoyuan City 32001, Taiwan

Received: 5 December 2019
Accepted: 20 February 2020

Abstract

The Yarkovsky effect plays an important role in asteroids drifting in the inner Solar System. In the main belt, many asteroids are continuously pushed by the Yarkovsky effect into regions of different mean motion resonances (MMRs) and then ejected after a period of time, due to the instability of MMRs. They are considered as the principal source of near-Earth objects. In this paper, we investigate the effects of the 7/3 MMR with Jupiter (J7/3 MMR) on the transportation of asteroids from the Koronis family and the Eos family that reside, respectively, on the inner and outer sides of the resonance using numerical simulations. The J7/3 MMR acts like a selective barrier to migrating asteroids. The fraction of asteroids that successfully cross through the resonance and the escape rate from the resonance are found to depend on the Yarkovsky drifting rate, the initial inclination and the migrating direction. The excitation of eccentricity and inclination due to the combined influence from both the resonance and the Yarkovsky effect are discussed. Only the eccentricity can be pumped up considerably, and it is attributed mainly to the resonance. In the observational data, family members are also found in the resonance and on the opposite side of the resonance with respect to the corresponding family centre. The existence of these family members is explained using our results of numerical simulations. Finally, the replenishment of asteroids in the J7/3 MMR and its transportation of asteroids are discussed.