4:30 PM - 4:45 PM
[PPS03-11] Comparison of the Size Distributions among Jupiter Trojan, Hilda, and Main-Belt Asteroids
Keywords:Jupiter Trojans, Hilda group, size distribution
We focus on the size distributions of the small JTs and Hildas for understanding their origins and evolutions. The shape of size distribution of a small-body population in collisional equilibrium is useful as a diagnostic marker for this study because it basically depends on the impact strength properties which are characterized by the body composition and internal structure. Comparison of size distributions allows us to evaluate the similarity between different small-body populations from the point of view of the physical properties.
We performed a wide-field survey targeting the L4 JTs using the 8.2-m Subaru Telescope and Hyper Suprime-Cam, a gigantic mosaic CCD camera with a wide field-of-view of 1.5 deg in diameter. As the result of our data analysis, 631 JTs and 130 Hildas were detected in the survey area of 26 square degrees in r-band (0.55-0.7 μm) images with the completeness limit of 24.4 mag corresponding to 1-2 km sized JT/Hilda astreoids. The size distributions derived from our unbiased samples including 481 JTs and 91 Hildas indicate that (i) JTs' size distribution can be represented by a single-slope power law between 2-10 km in diameter; (ii) Combining the size distribution of our JT sample with that of the known objects does not show a significant wavy pattern as seen in that of MBAs; (iii) The shape of Hildas' size distribution is indistinguishable from that of JTs in the kilometer size range. We also found that Hildas have a single-slope size distribution from 1 km to the largest bodies, implying that the Hilda population is in collisional equilibrium over the whole size range. The total number of Hildas larger than 2 km in diameter is estimated to be about 1 x 104, which is less than that of JTs by a factor of five.