Asteroid Discovery and Light Curve Extraction Using the Hough Transform -- A Rotation Period Study for Sub-Kilometer Main-Belt Asteroids

TL;DR

This study applies the Hough transform to high-cadence asteroid observations, successfully discovering thousands of faint sub-kilometer main-belt asteroids and determining their rotation periods, including super-fast rotators, revealing insights into their physical properties.

Contribution

It introduces a novel application of the Hough transform for asteroid detection and light curve extraction, enabling the discovery and rotation analysis of faint sub-kilometer main-belt asteroids.

Findings

Discovered 3574 new sub-kilometer main-belt asteroids.

Obtained 122 reliable rotation periods, including 13 super-fast rotators.

Super-fast rotators suggest low cohesion and a higher prevalence among small asteroids.

Abstract

The intra-night trajectories of asteroids can be approximated by straight lines, and so are their intra-night detections. Therefore, the Hough transform, a line detecting algorithm, can be used to connect the line-up detections to find asteroids. We applied this algorithm to a high-cadence Pan-STARRS 1 (PS1) observation, which was originally designed to collect asteroid light curves for rotation period measurements (Chang et al., 2019). The algorithm recovered most of the known asteroids in the observing fields and, moreover, discovered 3574 new asteroids with magnitude mainly of 21.5 < w_p1 < 22.5 mag. This magnitude range is equivalent to sub-kilometer main-belt asteroids (MBAs), which usually lack of rotation period measurements due to their faintness. Using the light curves of the 3574 new asteroids, we obtained 122 reliable rotation periods, of which 13 are super-fast rotators (SRFs; i.e., rotation period of < 2 hr). The required cohesion to survive these SFRs range from tens to thousands of Pa, a value consistent with the known SFRs and the regolith on the Moon and Mars. The higher chance of discovering SFRs here suggests that sub-kilometer MBAs probably harbor more SFRs.