Asteroids: Spins and Shapes

Abstract There is a difference in rotational properties between asteroids of various taxonomic types. The M and CMEU asteroids increase their spin with diameter and rotate much faster than asteroids of types C and S of the same diameter do. There is a difference in spin between the C and S types but the faster spin for the S asteroids larger than 150 km in diameter is probably not statistically significant. For both C and S asteroids the spin increases with diameter, but in a much less pronounced fashion than for types M and CMEU. The curve for the S asteroids is remarkably flat for asteroids smaller than 100 km. The CMEU asteroids are more irregular than other types of asteroids. Both C and S asteroids have larger amplitudes for diameters about 100 km. The family asteroids smaller than 100 km in diameter have a faster spin than non-family main-belt asteroids of the same size. Family asteroids show an increase of spin and lightcurve amplitude with decreasing diameter.