Fast and Slow Rotation of Asteroids

✍ Scribed by Petr Pravec; Alan W. Harris

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 113 KB
• Volume: 148
• Category: Article
• ISSN: 0019-1035
• DOI: 10.1006/icar.2000.6482

✦ Synopsis

We present an analysis of the distribution of asteroid spin rates vs. size. The existence of significant populations of both slow and fast rotators among asteroids smaller than D = 40 km, and especially below 10 km (where our sample is mostly near-Earth asteroids), is shown. We have found that the excess of slow rotators is present at spin rates below ≈0.8 rev/day, and the group of fast rotators occupies the range of spin rates >7 rev/day. The fast rotators show interesting characteristics: The lack of objects rotating faster than 2.2 h period among asteroids with absolute magnitude H < 22, as well as the tendency to spheroidal shapes of fast rotators, is evidence that asteroids larger than a few hundred meters are mostly loosely bound, gravity-dominated aggregates with negligible tensile strength ("rubble piles"), while monoliths may be abundant among smaller objects. A large fraction (about half) of near-Earth fast-rotating asteroids appear to be binary systems, probably created by tidal disruptions during close encounters with the terrestrial planets.