Distributions of spin axes and shapes of asteroids
Abstract
We developed a new simplified model for the determination of shapes and spin states of asteroids to fully exploit photometric data sparse in time (few measurements per night) which are produced by all-sky surveys and were re-calibrated into the Lowell photometric database by Bowell et al. (2014). We model asteroids as geometrically scattering triaxial ellipsoids. The model compares observed values of mean brightness and the dispersion of brightness with computed values obtained from the parameters of the model - ecliptical longitude λ and latitude β of the pole and the ratio a/b of axes of the ellipsoid. These parameters are optimized to get the best agreement with the observation. We revealed that the distribution of λ for the main-belt asteroids is anisotropic (in agreement with findings of Bowell et al. (2014)) and dependent on the inclination of orbit (for sin i < 0.04 there is an excess of λ ~ 70° +/- 180°). We are looking for a physical or observational mechanism that would explain this distribution. From the analysis of the distribution of a/b we found that larger asteroids (D > 25 km) are more often spherical (a/b ~ 1) than the smaller.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #47
- Pub Date:
- November 2015
- Bibcode:
- 2015DPS....4730710C