Binary Candidates in the Jovian Trojan and Hilda Populations from NEOWISE Lightcurves

TL;DR

This study uses NEOWISE lightcurve data to identify potential binary asteroids in the Jovian Trojan and Hilda populations, providing initial estimates of their binary fractions to inform solar system evolution models.

Contribution

It introduces a method to identify binary asteroid candidates from lightcurve amplitudes in NEOWISE data and provides preliminary binary fraction estimates for Trojans and Hildas.

Findings

Preliminary binary fraction estimate for Trojans: 14-23%.

Preliminary binary fraction estimate for Hildas: 30-51%.

Identified 82 binary candidates requiring follow-up confirmation.

Abstract

Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival dataset for close and contact binary Trojans and Hildas via their diagnostically large lightcurve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large lightcurve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14-23% for Trojans larger than ~12 km and 30-51% for Hildas larger than ~4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.