Title: A Wide-field Survey for Small Main-belt Asteroids in High Inclination
Authors: Tsuyoshi Terai, Yoichi Itoh
Abstract:
In the asteroid belt lying between the orbits of Mars and Jupiter, most bodies orbit along the ecliptic plane. But several asteroids have highly-inclined orbits which are suffered by strong dynamical excitation. Here if the protoplanetary gas disk was present during the phase of asteroid excitation, asteroids' inclination would be damped by gas drag, which is more effective on smaller bodies. The lifetime of disk gas is very important for the growth of planets, but it is still unknown in which stage of planet formation the disk gas was depleted from the solar system. We could provide some constraints on the timing of gas dissipation by comparing the size distribution between low- and high- inclination small main-belt asteroids (MBAs).
To investigating the population of high-inclination sub-km MBAs, we performed a wide-field survey in the high ecliptic latitude using Subaru telescope with Subaru Prime Focus Camera (Suprime-Cam). Our survey campaign resulted in the detection of more than 600 MBA candidates in 9.0 square degrees of sky. The estimated diameters of the detected bodies range from 0.7 km to 5 km. We found that the abundance of sub-km bodies in the high-inclination group is clearly smaller than that in the low-inclination one. This indicates that gas drag might have operated during the orbital evolution of high-inclination MBAs.