Detection of Contact Binaries Using Sparse High Phase Angle Lightcurves

TL;DR

This paper demonstrates that sparse photometric observations at high phase angles can efficiently identify candidate contact binary asteroids by their distinctive lightcurve patterns, aiding in understanding near-Earth object populations.

Contribution

It introduces a method to detect contact binary asteroids using only a few high phase angle observations, improving survey efficiency.

Findings

Sparse observations at >60° phase angle reveal contact binaries.

Lightcurve features include large brightness variations (>1 mag).

Method can determine the spin sense of asteroids.

Abstract

We show that candidate contact binary asteroids can be efficiently identified from sparsely sampled photometry taken at phase angles >60deg. At high phase angle, close/contact binary systems produce distinctive lightcurves that spend most of the time at maximum or minimum (typically >1mag apart) brightness with relatively fast transitions between the two. This means that a few (~5) sparse observations will suffice to measure the large range of variation and identify candidate contact binary systems. This finding can be used in the context of all-sky surveys to constrain the fraction of contact binary near-Earth objects. High phase angle lightcurve data can also reveal the absolute sense of the spin.