WISE /NEOWISE OBSERVATIONS OF THE HILDA POPULATION: PRELIMINARY RESULTS

• Published in: Astrophysical journal. Letters 2012-01, Vol.744 (2), p.1-15
• Main Authors: Grav, T, Mainzer, A K, Bauer, J, Masiero, J, Spahr, T, McMillan, R S, Walker, R, Cutri, R, Wright, E, Eisenhardt, P R, Blauvelt, E, DeBaun, E, Elsbury, D, GAUTIER IV, T, Gomillion, S, Hand, E, Wilkins, A
• Format: Article
• Language: English
• Subjects: ALBEDO; Asteroid collisions; ASTEROIDS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLASSIFICATION; Infrared; INFRARED SURVEYS; PLANETS; SOLAR SYSTEM; Sunlight
• ISSN: 0004-637X; 2041-8205; 1538-4357; 2041-8213
• DOI: 10.1088/0004-637X/744/2/197

We present the preliminary analysis of 1023 known asteroids in the Hilda region of the solar system observed by the NEOWISE component of the Wide-field Infrared Survey Explorer (WISE). The sizes of the Hildas observed range from ~3 to 200 km. We find no size-albedo dependency as reported by other projects. The albedos of our sample are low, with a weighted mean value of p sub(V) = 0.055 + or - 0.018, for all sizes sampled by the NEOWISE survey. We observed a significant fraction of the objects in the two known collisional families in the Hilda population. It is found that the Hilda collisional family is brighter, with a weighted mean albedo of p sub(V) = 0.061 + or - 0.011, than the general population and dominated by D-type asteroids, while the Schubart collisional family is darker, with a weighted mean albedo of p sub(V) = 0.039 + or - 0.013. Using the reflected sunlight in the two shortest WISE bandpasses, we are able to derive a method for taxonomic classification of ~10% of the Hildas detected in the NEOWISE survey. For the Hildas with diameter larger than 30 km, there are 67 sub(-15) super(+7)% D-type asteroids and 26 sub(-5) super(-17)% C-/P-type asteroids (with the majority of these being P-types).