BVRI photometry of 53 unusual asteroids

TL;DR

This study presents BVRI photometry and classification of 53 unusual asteroids, including NEAs and asteroid pairs, and merges data from multiple surveys to analyze spectral type distributions and size-related surface weathering effects.

Contribution

It provides the first detailed photometric classification of 53 unusual asteroids and merges data to analyze spectral type ratios across different size ranges.

Findings

Most asteroids were not previously classified.

The C/X-like to S-like ratio increases for smaller NEAs.

Supports the hypothesis that smaller NEAs have less weathered surfaces.

Abstract

We present the results of BVRI photometry and classification of 53 unusual asteroids, including 35 near-Earth asteroids (NEAs), 6 high eccentricity/inclination asteroids, and 12 recently-identified asteroid-pair candidates. Most of these asteroids were not reportedly classified prior to this work. For the few asteroids that have been previously studied, the results are generally in rough agreement. In addition, we merge the results from several photometric/spectroscopic surveys to create a largest-ever sample with 449 spectrally classified NEAs for statistical analysis. We identify a "transition point" of the relative number of C/X-like and S-like NEAs at H~18<=>D~1km with confidence level at ~95% or higher. We find that the C/X-like:S-like ratio for 18<=H<22 is about two times higher than that of H<18 (0.33+/-0.04 versus 0.17+/-0.02), virtually supporting the hypothesis that smaller NEAs generally have less weathered surface (therefore, less reddish appearance) caused by younger collision ages.