Gravitational re-accumulation as the origin of most contact binaries and other small body shapes

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2020-03, Vol.339, p.113603, Article 113603
• Main Authors: Campo Bagatin, Adriano, Alemañ, Rafael A., Benavidez, Paula G., Pérez-Molina, Manuel, Richardson, Derek C.
• Format: Article
• Language: English
• Subjects: Asteroid shapes; Asteroids; Collisional physics; Contact binaries
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2019.113603

Asteroids show a variety of shapes, ranging from roundish to elongated to binary systems and ‘contact binaries’ like (25143) Itokawa, the target of the Hayabusa mission (JAXA). These bodies spend most of their time within a collisional system, the asteroid belt, where impact processes are relatively frequent. Speculations on the origin of asteroid shapes invoke mechanisms such as collisions and spin-up effects. N-body numerical simulations of fragment evolution following catastrophic collisions have been recently carried out (Campo Bagatin et al., 2018). In this study the idea that the stochastic process of gravitational re-accumulation may be responsible for many observed asteroid shapes is introduced. Asteroid ‘contact binaries’ are shown to be regularly produced by the gravitational re-accumulation process following catastrophic impact. Similar processes may have occurred in the case of some comets and Trans-Neptunian Objects. •Contact binary asteroids can be formed by gravitational re-accumulation.•Rubble-pile asteroid shape formation is ruled by stochastic low speed collisions.•Asteroid satellites formed during re-accumulation may be single shards.•Largest fragments are not necessarily in the center of asteroid rubble-piles.