Space Weathering Trends Among Carbonaceous Asteroids

TL;DR

This study compares space weathering effects on two asteroid families, showing that weathering makes C-complex asteroids redder and darker, with variations linked to size and composition, revealing insights into asteroid surface evolution.

Contribution

It provides new spectroscopic and albedo data for the Themis and Beagle asteroid families, highlighting how space weathering and regolith variations affect their surface properties.

Findings

C-complex asteroids become redder and darker due to weathering.

Phyllosilicate features are less common in smaller Themis asteroids.

Beagle family members show signs of heterogeneity with some containing phyllosilicates.

Abstract

We present visible spectroscopic and albedo data of the 2.3 Gyr old Themis family and the <10 Myr old Beagle sub-family. The slope and albedo variations between these two families indicate C-complex asteroids become redder and darker in response to space weathering. Our observations of Themis family members confirm previously observed trends where phyllosilicate absorption features are less common among small diameter objects. Similar trends in the albedos of large (> 15 km) and small (< 15 km) Themis members suggest these phyllosilicate feature and albedo trends result from regolith variations as a function of diameter. Observations of the Beagle asteroids show a small, but notable fraction of members with phyllosilicate features. The presence of phyllosilicates and the dynamical association of the main-belt comet 133P/Elst-Pizarro with the Beagle family imply the Beagle parent body was a heterogenous mixture of ice and aqueously altered minerals.