The origin of long-lived asteroids in the 2:1 mean-motion resonance with Jupiter

Abstract

The 2:1 mean-motion resonance with Jupiter harbours two distinct groups of asteroids. The short-lived population is known to be a transient group sustained in steady state by the Yarkovsky semimajor axis drift. The long-lived asteroids, however, can exhibit dynamical lifetimes comparable to 4 Gyr. They reside near two isolated islands of the phase space denoted A and B, with an uneven population ratio B/A ≃ 10. The orbits of A-island asteroids are predominantly highly inclined, compared to island B. The size-frequency distribution is steep but the orbital distribution lacks any evidence of a collisional cluster. These observational constraints are somewhat puzzling and therefore the origin of the long-lived asteroids has not been explained so far.With the aim to provide a viable explanation, we first update the resonant population and revisit its physical properties. Using an N -body model with seven planets and the Yarkovsky effect included, we demonstrate that the dynamical depletion of island A is faster, in comparison with island B. Then we investigate (i) the survivability of primordial resonant asteroids and (ii) capture of the population during planetary migration, following a recently described scenario with an escaping fifth giant planet and a jumping-Jupiter instability. We also model the collisional evolution of the resonant population over past 4 Gyr. Our conclusion is that the long-lived group was created by resonant capture from a narrow part of hypothetical outer main-belt family during planetary migration. Primordial asteroids surviving the migration were probably not numerous enough to substantially contribute to the observed population.

Strength, stability and three dimensional structure of mean motion resonances in the solar system

“…We are used to the shape of the resonances in the plane (a, e) for near zero inclination orbits (see for example figure 2 in Nesvorný et al (2002)) but very few studies have been done in the space (a, i) (Callegari and Yokoyama, 2010; Chrenko et al, 2015;Namouni and Morais, 2018). In figure 17 we show four dynamical maps of ∆a in the plane (a, i) obtained for the resonance 3:1 with Jupiter assuming ω = 0 • , each one corresponding to a given eccentricity for the test particles.…”

White dwarf pollution by asteroids from secular resonances

“…To take our Solar system as an example, many asteroids are located in the asteroid belt between Mars and Jupiter. Over time, some asteroids undergo resonant gravitational perturbations from the two largest planets, Jupiter and Saturn, causing the asteroids to become scattered from the asteroid belt (Morbidelli et al 1995;Gladman et al 1997;Morbidelli & Gladman 1998;Bottke et al 2000;Petit et al 2001;Ito & Malhotra 2006;Brož & Vokrouhlický 2008;Minton & Malhotra 2010;Chrenko et al 2015;Granvik et al 2017). In a mean-motion resonance, the ratio of the orbital periods of two objects is an integer ratio (e.g.…”

Asteroid impacts on terrestrial planets: the effects of super-Earths and the role of the ν6 resonance

“…The transparent yellow box denotes the observed super-Earths with a semi-major axis in the inner solar system. The data are from exoplanets.org (Han et al 2014). 1997; Morbidelli & Gladman 1998;Petit et al 2001;Brož & Vokrouhlický 2008;Minton & Malhotra 2010;Chrenko et al 2015) leading to the formation of potential Earth impactors (Morbidelli & Nesvorný 1999;Strom et al 2005).…”