NEOWISE: The Cybele population
Abstract
The Nice model is currently favored as the leading hypothesis for quantitatively explaining many of the characteristics seen in the current Solar System, from the giant planet orbits, the Jovian and Neptunian Trojan populations, the Kuiper Belt, and the origin of the late heavy bombardment (Tsiganis et al., 2005; Morbidelli et al., 2005; Nesvorny et al., 2007). The insertion of primitive trans-Neptunian objects into the outer main belt using the Nice model can reproduce the general aspects of both the taxonomic and size distributions seen in the outer main belt, Hilda, and Jovian Trojan populations. Deeper understanding of the current taxonomy, sizes, and physical properties of these populations is needed to better constrain the Nice model. In previous papers we have reported on these properties for the Hilda and Jovian Trojan populations based on mid-infrared observations of the NEOWISE extension of the Wide-field Infrared Survey (WISE) mission (Grav et al., 2011a, 2011b, 2012). Here we report on the results of the NEOWISE observations of the Cybele population. The Cybeles are asteroids that occupy the region just beyond the edge of the main asteroid belt, with semi major axis between the 2:1 (at 3.27AU) and 5:3 (at 3.7AU) mean motion resonances with Jupiter. The Cybeles currently consist of over 3000 known objects. Generally thought of as a breakup of a large asteroid in the early part of the formation of the Solar System, the Cybeles are dominated by the primitive C, P and D taxonomic classes from the Tholen taxonomic system (Tholen & Barucci, 1989). To test whether the Cybele population has experienced significant shattering events after insertion it is important to determine the size distribution of this population. Here we present the thermal observations of over 1200 objects from the Cybele population, using the WISE satellite during its cryogenic phase. The thermal model fits show a mostly homogeneous population. A vast majority of the Cybeles are dark, with albedos of less then 10%. Preliminary results show that the mean albedo of the Cybeles is 5±3%, which is similar to that of the Hilda population (5.5±1.8%; Grav et al. 2012), and darker than the Jovian Trojan Population (7±3; Grav et al., 2011).
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #50
- Pub Date:
- October 2018
- Bibcode:
- 2018DPS....5041405G