NEOWISE: Observations of the Irregular Satellites of Jupiter and Saturn

TL;DR

This study uses NEOWISE data to determine sizes and reflectance properties of irregular satellites of Jupiter and Saturn, confirming previous measurements and revealing new data that suggest common origins with other small Solar System bodies.

Contribution

First thermal modeling of 12 irregular satellites providing diameters and albedos, confirming spacecraft measurements and linking their properties to other small body populations.

Findings

Confirmed diameters for Himalia and Phoebe with in situ data

Provided new size and albedo data for 10 Jovian and 2 Saturnian satellites

Found reflectance properties similar to Jovian Trojans and Hildas

Abstract

We present thermal model fits for 11 Jovian and 3 Saturnian irregular satellites based on measurements from the WISE/NEOWISE dataset. Our fits confirm spacecraft-measured diameters for the objects with in situ observations (Himalia and Phoebe) and provide diameters and albedo for 12 previously unmeasured objects, 10 Jovian and 2 Saturnian irregular satellites. The best-fit thermal model beaming parameters are comparable to what is observed for other small bodies in the outer Solar System, while the visible, W1, and W2 albedos trace the taxonomic classifications previously established in the literature. Reflectance properties for the irregular satellites measured are similar to the Jovian Trojan and Hilda Populations, implying common origins.