The Role of the Yarkovsky Effect in the Long-term Dynamics of Asteroid (469219) Kamo’oalewa

Abstract

The Near-Earth asteroid (469219) Kamo’oalewa (aka 2016 HO3) is an Earth coorbital and a potential space mission target. Its short-term dynamics are characterized by a periodic switching between quasisatellite and horseshoe configurations. Due to its small diameter of only about 36 m, the Yarkovsky effect may play a significant role in the long-term dynamics. In this work, we addressed this issue by studying the changes in the long-term motion of Kamo’oalewa caused by the Yarkovsky effect. We used an estimation of the magnitude of the Yarkovsky effect assuming different surface compositions and introduced the semimajor axis drift by propagating orbits of test particles representing the clones of the nominal orbit. Our simulations showed that the Yarkovsky effect may cause Kamo’oalewa to exit from the Earth coorbital region a bit faster when compared to a purely gravitational model. Nevertheless, it still could remain an Earth companion for at least 0.5 My in the future. Our results imply that Kamo’oalewa is the most stable Earth’s coorbital object known so far, not only from a short-term perspective but also on long timescales.

Orbital pathways for a Lunar-Ejecta Origin of the Near-Earth Asteroid Kamo`oalewa

“…In the regime of large eccentricity and inclination, [2] has attributed such transitions to a secular drift of the asteroid's perihelion and [11] has suggested this as a mechanism that applies to Kamo'oalewa. While the eventual escape from co-orbital states may be linked to planetary secular perturbations [41][42][43], or to planetary close encounters [44], or to Yarkovsky-driven migration [9], it is likely that the short-time transport dynamics of Kamo'oalewa are governed by the invariant-manifold structure of the Lagrange points [39,45,46]. For example, [46] attribute the entry and escape mechanisms of Kamo'oalewa's HS-QS transitions to such phase-space structures, but [34] invoke chaotic tangles of the Lagrange points to explain the dynamical mechanisms of capture into sticky QS orbits.…”

“…An assessment of Earth's co-orbital companions shows a total population of only twenty-one objects, with two Trojan-type, six in the QS state, and thirteen undergoing HS motion; all of these objects are in their co-orbital states only temporarily, typically on less than decadal timescales [4,5]. The recently discovered quasisatellite of the Earth, (469219) Kamo'oalewa, is exceptional among the Earth's co-orbitals due to the longer-term persistence of its HS-QS transitions [6][7][8][9].…”

Dynamical evolution of basaltic asteroids outside the Vesta family in the inner main belt

“…In the next step, we used a more complex model with the Yarkovsky effect. Details of the thermal parameters of the asteroids used in this model (Fenucci & Novakovic 2021): bulk density 3000 kg m −3 ; surface density 1500 kg m −3 ; surface emissivity 0.95; thermal conductivity 0.001 W K −1 m −1 ; thermal capacity of 680 J kg −1 K −1 for all objects and data from Table 2.…”

Physical and dynamical properties of selected Earth co-orbital asteroids

“…Here, and contain the eigenvec- One question to be asked here is whether including the size-dependent Yarkovsky drag force in our dynamical model might change the outcome in a significant way. Fenucci and Novaković (2020) investigated this question for the Earth quasi-satellite (469219) Kamo'oalewa, an object comparable in both size and orbit to the smallest object in our sample, 2017 SL16. Though Yarkovsky does change the orbital evolution of Kamo'oalewa over millions of yr and its residence time as an Earth co-orbital, actual differences from the gravity-only case were quite small and the overall effect on the evolution of the orbit was not significant.…”