AKARI/AcuA Physical Studies of the Cybele Asteroid Family
Hasegawa, Sunao; Usui, Fumihiko; Ootsubo, Takafumi; Ishiguro, Masateru; Müller, Thomas G.; Kuroda, Daisuke; Kasuga, Toshihiro
Japan, Germany, South Korea
Abstract
We present a study of 107 Cybele asteroids based on the archival database "Asteroid Catalog Using AKARI (AcuA)" taken by the Infrared Astronomical Satellite. The database provides diameters D > 10 km, geometric albedos, and taxonomic information (75%) of the Cybeles. We find taxonomic diversity (mainly C-, D-, and P-type) in the population of 78 small Cybeles with diameters 10 km <D < 80 km. Their cumulative power-law size distribution index shows a shallow value of 0.86 ± 0.03. By contrast, 29 large Cybeles with D > 80 km are mostly classified as C- or P-types (90%), with a power-law index of 2.39 ± 0.18. The total mass of Cybele asteroids is estimated to be ~10-5 M Earth. We also discuss the origin and formation process of the Cybele asteroid family.