Formation and Destruction of Small Binary Asteroids
Open Access
- 5 March 2007
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 659 (1), L57-L60
- https://doi.org/10.1086/516572
Abstract
Our understanding of binary asteroids is currently undergoing major revisions. Until recently, all known small binaries (primary diameters 1 km) were near-Earth asteroids (NEAs), making it plausible that they originate in close encounters with terrestrial planets, and were not to be found among the main belt asteroids (MBAs). First simulations of tidal disruption have produced incidence of binaries that roughly matched the observed fraction of binary NEAs. Thermal-radiation effects, most notably YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack), were not needed to explain the life cycle of binary asteroids, despite some theoretical arguments in favor of significant YORP evolution. Recent discovery of abundant small MBA binaries and a more self-consistent reassessment of effects of planetary encounters have put the primacy of planetary encounters in doubt and shown a need for new theoretical explanations. Here I show that the mass loss from the primary's surface due to YORP could explain the formation of kilometer-sized binary NEAs. I also suggest that the small-separation NEA binaries' observed properties are consistent with evolution through "binary YORP," rather than tidal stripping during planetary passages (when the pairs evolve beyond ~10 primary radii, encounters become important). Such a life cycle implies not only the extreme youth of small binary asteroids (5 yr) but also short timescales for large-scale mass redistribution on most kilometer-sized asteroids, leading to a near-complete lack of craters on their surfaces.Keywords
This publication has 24 references indexed in Scilit:
- Radar Imaging of Binary Near-Earth Asteroid (66391) 1999 KW4Science, 2006
- Near-Earth Asteroid 2005 CR37: Radar images and photometry of a candidate contact binaryIcarus, 2006
- Detailed Images of Asteroid 25143 Itokawa from HayabusaScience, 2006
- Photometric survey of binary near-Earth asteroidsIcarus, 2005
- Effects of thermal radiation on the dynamics of binary NEAsIcarus, 2005
- The Orbit and Albedo of Trans-Neptunian Binary (58534) 1997 CQ29The Astronomical Journal, 2004
- A three-dimensional solution for the orbit of the asteroidal satellite of 22 KalliopeIcarus, 2003
- Binary Asteroids in the Near-Earth Object PopulationScience, 2002
- Resonances in the Early Evolution of the Earth-Moon SystemThe Astronomical Journal, 1998
- Tidal rigidity of phobosIcarus, 1982