Statistical analysis of C and S Main Belt Asteroids

TL;DR

This study compares the observable properties of C and S Main Belt Asteroids, revealing similarities in their size and rotational characteristics, with some biases and differences at smaller diameters, suggesting homogeneous collisional evolution.

Contribution

It provides a detailed statistical comparison of C and S asteroids' properties, highlighting their similarities and differences across size ranges and their implications for collisional processes.

Findings

Similar diameter distributions above 20 km for C and S asteroids

Significant correlation between rotation frequency and diameter for both types

No substantial differences in rotational properties indicating homogeneous collisional evolution

Abstract

In this paper we compare the observable properties of 962 numbered MBAs (Main Belt Asteroids) of Tholen/SMASSII C and S class, with diameter in the range 1-500 km, not belonging to families or binary systems. Above 20 km, the diameters distributions of C and S are similar while under 20 km there is a clear observative bias in favour of small S asteroids which prevents a direct comparison. There is a significant correlation between rotation frequency and diameter both for C and S: if the diameter decreases the rotation frequency tends to increase. There is also a significant correlation between the lightcurve amplitude and the diameter for both samples: if the diameter decreases the lightcurve amplitude tends to increase. For larger diameter the C amplitude tends to be systematically higher than S amplitude of about 0.1 magnitude, but the difference is not very significant. Between 48 and 200 km, the C asteroids have a rotation frequency distribution compatible with a Maxwellian. On the other side, for S asteroids, the compatibility with the Maxwellian concernes diameters greater than 33 km. Considering the rotational properties and the lightcurve amplitude it appears that there are no substantial differences between the samples of C and S asteroids taken into account, and this indicates a good homogeneity in the processes of collisional evolution.