Speaker
Description
Bi-lobed objects (contact binaries) consist of between 15-30% of near-Earth objects (NEOs) and also appear in the main asteroid belt, Kuiper belt, and comet populations. Notable contact binaries include Itokawa - visited by the Hayabusa mission, Selam - visited by the LUCY mission, and 67P which was visited by the Rosetta mission. We use archival radar observations in combination with optical lightcurves to constrain the spin states of a small selection of these objects and create detailed shape models using the SHAPE modelling software. Radar observations are crucial for modelling the neck structure and any other concavities or craters on the surface of the objects, as optical observations are not sufficient to unambiguously reproduce details such as depth or shapes of such features. Radar observations, however, can contain shape and distance observations to resolutions down to only 2.5 meters. From these models, we can estimate the objects' sizes, bulk and surface densities, and physical compositions. This allows us to make inferences on their possible formation histories and scenarios for how they might have evolved, and better characterise the different types of contact binaries that we observe. We are creating several of these shape models using radar data from both the Goldstone and Arecibo observatories to investigate any notable similarities or differences between these asteroids.
