Searching for color variation on fast rotating asteroids with simultaneous V-J observations

TL;DR

This study introduces a simultaneous V-J observation technique to detect color variations on fast rotating asteroids, aiming to identify surface changes like landslides and exposure of fresh material.

Contribution

The paper presents a novel simultaneous visible and near-IR observation method for asteroids, enabling detection of surface color variations related to geological activity.

Findings

Detected ~5% variation in V-J color among observed asteroids.

No clear repeating color signature was found across multiple rotations.

Results suggest no recent landslides or that exposed patches are below detection limits.

Abstract

Boulders, rocks and regolith on fast rotating asteroids (<2.5 hours) are modeled to slide towards the equator due to a strong centrifugal force and a low cohesion force. As a result, regions of fresh subsurface material can be exposed. Therefore, we searched for color variation on small and fast rotating asteroids. We describe a novel technique in which the asteroid is simultaneously observed in the visible and near-IR wavelength range. In this technique, brightness changes due to atmospheric extinction effects can be calibrated across the visible and near-IR images. We use V- and J-band filters since the distinction in color between weathered and unweathered surfaces on ordinary chondrite-like bodies is most prominent at these wavelengths and can reach ~25%. To test our method, we observed 3 asteroids with Cerro Tololo's 1.3 m telescope. We find ~5% variation of the mean V-J color, but do not find any clearly repeating color signature through multiple rotations. This suggests that no landslides occurred within the timescale of space weathering, or that Landslides occurred but the exposed patches are too small for the measurements' uncertainty.