Centaurs potentially in retrograde co-orbit resonance with Saturn

Abstract

Aims. 2015 BZ509 is the first asteroid confirmed to be in retrograde co-orbit resonance (or 1/-1 resonance) with the giant planets in the solar system. While Saturn is the only giant planet whose Trojans are not discovered until now, we identify some small bodies among Centaurs and Damocloids that are potentially in 1/-1 resonance with Saturn in the present study. Methods. We integrate numerically the motion of the 1000 clones (include the nominal orbit) of each Centaur whose orbit has a semimajor axis between 9.3 au and 9.8 au and an inclination i > 90 • . To confirm and evaluate the 1/-1 resonant configurations mentioned above, we introduce an useful one degree integrable approximation for planar 1/-1 resonance. Results. We identify four candidates potentially in 1/-1 resonance with Saturn. The capture in this particular resonant state during the 40000 yr integration timespan is very common for 2006 RJ2 (906/1000 clones), 2006 BZ8 (878/1000 clones), and 2017 SV13 (998/1000 clones), and it is less likely for 2012 YE8 (426/1000 clones). According to our statistical results, 2006 RJ2 is the best candidate to be currently in a 1/-1 mean motion resonance with Saturn, and 2017 SV13 is another important potential candidate. Moreover, 2012 YE8 and2006 BZ8 are also Centaurs of interest but their current and long-term 1/-1 resonant state with Saturn is less likely. The proportions of the clones captured in the relative long-term stable co-orbit resonance (over 10000 yr) are also given. The motions of the 2006 RJ2, 2015 BZ509, and 2006 BZ8 in the solar system are just around the ideal equilibrium points of the 1/-1 resonance given by the planar semi-analytical model. Conclusions. Small bodies in retrograde co-orbit resonance with giant planets may be more common than previously expected. Identification of these potential mysterious minor bodies encourages the search for such objects on a larger scale in our solar system. The findings of this paper are also useful for understanding the origin and dynamical evolution of the Centaurs and Damocloids on retrograde orbits.

Kozai-Lidov mechanism inside retrograde mean motion resonances

“…In our recently published paper, Li et al (2018) identifies four candidates potentially trapped in the retrograde 1:1 resonance with Saturn, 2006RJ2, 2006BZ8, 2017SV13, and 2012 YE8. Among these candidates, only 2006 RJ2 has a relatively long-time resonant state with Saturn (above 100 kyr), in which the resonant Kozai-Lidov dynamics is able to influence the orbital evolution of the minor body significantly.…”

“…Moreover, we compare the numerical results in a CRTBP model with the semianalytical phase-space portraits. In Section 4, we utilize this method to analyze the Kozai-Lidov state of two real minor bodies inside the retrograde 1:1 resonance, they are, 2015 BZ509 and 2006 RJ2, the latter is confirmed to be in the retrograde 1:1 resonance with Saturn by Li et al (2018). Finally, in Section 5, we apply this methodology to two more retrograde resonances, 2:1 and 2:5, and find different bifurcations of equilibrium points with phase-space portraits.…”

Dynamical structures of retrograde resonances: analytical and numerical studies

“…Recently, Connors & Wiegert (2018) reported that asteroid 2007 VW266 (a retrograde object near Jupiter's orbit) is inside a retrograde 13:14 resonance with Jupiter. Li et al (2018) numerically explored the resonant behaviors of the clones for the minor bodies among Centaurs and Damocloids and they identified another four Centaurs (including 2006RJ2, 2006BZ8, 2017SV13 and 2012, which are potential candidates inside retrograde co-orbital resonances with Saturn. Furthermore, Li et al (2019) numerically investigated the possible retrograde resonant configurations of minor objects in the Solar system and they identified 38 asteroids to be trapped inside retrograde MMRs with planets.…”

On the instability of Saturn’s hypothetical retrograde co-orbitals

“…It seems that former researchers have put an end to the problem. However, the latest discoveries of the first retrograde co-orbital body of Jupiter (Wiegert et al 2017) and potential retrograde co-orbitals of Saturn (Li et al 2018) have once again ignited our curiosity to the co-orbital region of Saturn. In the process of studying the dynamics of retrograde resonances (Huang et al 2018a,b), we noticed that Saturn's retrograde co-orbital region is significantly unstable.…”