Spin Rate Distribution of Small-Sized Main Belt Asteroids
Department of Geophysics and Planetary Sciences
Photometry of asteroids allows the derivation of their spins around their axis. Enlarging the statistics of asteroids' spins enables one to study physical mechanisms that affect the spin evolution of asteroids in correlation with their orbits, sizes and compositions.
We conduct an extended campaign of asteroid photometry at the Wise Observatory using a wide-field CCD on a semi-automated telescope. With it, we succeeded to obtain results for a population that has hardly been measured by now – small Main Belt Asteroids (MBAs) in the size range of one to three km.
We added our derived spin periods to data from the literature and compared the spin rate distributions of small MBAs with that of bigger asteroids and of similar-sized Near-Earth Asteroids (NEAs). We found that the spin rate distribution of small MBAs does not show the clear Maxwellian-shaped distribution as large asteroids do; rather they have a spin rate distribution similar to that of NEAs. This implies that non-Maxwellian spin rate distribution is primarily controlled by the asteroids' sizes rather than their locations.