Dynamical study of Geminid formation assuming a rotational instability scenario

Abstract

Various ideas have been proposed to explain the formation of the Geminid meteoroid stream from the asteroid (3200) Phaethon. However, little has been studied regarding whether the Geminid formation could be the result of mass ejection via rotational instability of this asteroid. In this work, we present the first dynamical study of the Geminid formation taking into account low-velocity mass ejection caused by Phaethon's rotational instability. We conducted numerical simulations for 1-mm and 1-cm particles ejected in a wide range of ejection epochs (10$^3$--10$^5$ years ago). We computed the minimum orbital intersecting distance (MOID) of the dust particles as the realistic condition, that is, the Earth's radius and the Earth-Moon distance to be observed as the Geminid meteoroid stream. We found that the low-velocity ejection model produced the Geminid-like meteoroid stream when the dust particles were ejected more than sim 2,000 years ago. In this case, close encounters with terrestrial planets would transport some dust particles from the Phaethon orbit (the current MOID is as large as sim 460 Earth radii) to the Earth-intersecting orbits. The optimal ejection epoch and the estimated mass were 18\,000 years ago and $ $ g (<0.1 <!PCT!> of the Phaethon mass). Our results suggest that the JAXA DESTINY mission has the potential to find evidence of recent rotational instability recorded on the surface of Phaethon.

The Sensitivity of NEO Surveyor to Low-perihelion Asteroids

“…Given that the currently observed levels of activity are insufficient to populate the Geminid stream (Jewitt & Li 2010), such a breakup event could naturally resolve this discrepancy. Devogèle et al (2020) showed that the physical properties of Phaethon and 2005 UD are consistent, strengthening the proposed link, while dynamical modeling by Jo & Ishiguro (2024) finds an optimal epoch of dust creation ∼18 kyr ago. A fission event large enough to create the Geminid stream and 2005 UD from a proto-Phaethon body would also be expected to produce a number of intermediate sized objects in the range of tens to hundreds of meters that would still be present in the NEO population today, based on observed outcomes of rotational (Jewitt et al 2017) and tidal (Sekanina et al 1994) breakups.…”