WISE Observations of Primitive Asteroid Families

NASA's Wide-field Survey Explorer (WISE) mapped the sky in four bands at 3.4, 4.6, 12, and 22 μm during its mission. Published on 14 April 2011, the WISE Preliminary Release provides data of more than 150,000 asteroids that were processed with initial calibration and reduction algorithms. Our aim is to carry out an analysis of key physical parameters (size, albedo, and thermal properties) of outer main-belt asteroid families. Our study concentrates on the Themis, Veritas, and Hygeia families, but will also include other primitive families (taxonomic types C, P, and D). For each of our target asteroids in the WISE preliminary release, we estimated diameters and albedos by fitting thermal models to the measured fluxes, thus constraining their size distribution and compositions. Our initial results from WISE are part of a more extensive study that includes visible, near-infrared, and mid-infrared spectroscopy. These asteroid families are believed to have experienced less heating than most other asteroids and comparisons with Jupiter Trojans, cometary nuclei, and primitive meteorites can provide strong tests of dynamical and collisional models that relate outer belt asteroids with Transneptunian objects.