The morphology of contact binary objects in the Solar System

Abstract

Contact binaries, appearing as two objects stuck together, are prevalent throughout the Solar System, making up between 30-50% of asteroids and comets. Despite this, detailed shape models of contact binaries are hard to obtain remotely, requiring rare occultation events or close approaches to Earth (<0.1 au) to observe with ground-based radar systems. Despite only 16 contact binary models being published, there already exists a wide variety of different arrangements of the two lobes relative to one another. At the same time, simulations of contact binary object formation are increasing in scale, producing 10s to 1000s of contact binary candidates per simulation. It is therefore necessary to begin the process of characterising the different shapes observed, and to further investigate any emerging trends. We analyse the size, period, neck prominence, volume distribution, ratio between the sizes and volumes of the individual lobes, and the alignment between them to summarise the extent of the currently modelled asteroids.