Evidence for a colour dependence in the size distribution of main belt asteroids

Abstract

We present the results of a project to detect small (~1 km) main-belt asteroids with the 3.6 meter Canada-France-Hawaii Telescope (CFHT). We observed in 2 filters (MegaPrime g' and r') in order to compare the results in each band. Owing to the observational cadence we did not observe the same asteroids through each filter and thus do not have true colour information. However strong differences in the size distributions as seen in the two filters point to a colour-dependence at these sizes, perhaps to be expected in this regime where asteroid cohesiveness begins to be dominated by physical strength and composition rather than by gravity. The best fit slopes of the cumulative size distributions (CSDs) in both filters tend towards lower values for smaller asteroids, consistent with the results of previous studies. In addition to this trend, the size distributions seen in the two filters are distinctly different, with steeper slopes in r' than in g'. Breaking our sample up according to semimajor axis, the difference between the filters in the inner belt is found to be somewhat less pronounced than in the middle and outer belt, but the CSD of those asteroids seen in the r' filter is consistently and significantly steeper than in g' throughout. The CSD slopes also show variations with semimajor axis within a given filter, particularly in r'. We conclude that the size distribution of main belt asteroids is likely to be colour dependent at kilometer sizes and that this dependence may vary across the belt.

28 pages, 5 figures, submitted to the Astronomical Journal

References in corpus (5)

• The USNO-B Catalog
• Catastrophic disruptions revisited
• Solar System Objects Observed in the SDSS Commissioning Data
• Steady-State Size Distributions for Collisional Populations: Analytical Solution with Size-Dependent Strength
• The Orbital and Absolute Magnitude Distributions of Main Belt Asteroids

Cited by in corpus (15)

• Self-consistent size and velocity distributions of collisional cascades
• Transient outburst events from tidally disrupted asteroids near white dwarfs
• Solar System Science with ESA Euclid
• Portrait of Theobalda as a Young Asteroid Family
• Searching for Main-Belt Comets Using the Canada-France-Hawaii Telescope Legacy Survey
• EURONEAR - Recovery, Follow-up and Discovery of NEAs and MBAs using Large Field 1-2m Telescopes
• A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum
• Asteroids' Size Distribution and Colors from HiTS
• Where are the Mini Kreutz-family Comets?
• Size distributions of bluish and reddish small main-belt asteroids obtained by Subaru/Hyper Suprime-Cam
• The Flux Distribution and Sky Density of 25th Magnitude Main Belt Asteroids
• Thermophysical Modeling of 20 Themis Family Asteroids with WISE/NEOWISE Observations
• Size Distribution of Main-Belt Asteroids with High Inclination
• Constraints on Comet 332P/Ikeya-Murakami
• A Dedicated Lunar Trojan Asteroid Survey with Small Ground-Based Telescopes