演講資訊

摘要：

The giant planets in the Solar System all have satellites with large inclined eccentric orbits that are known as irregular moons. Due to their short orbital periods and relatively small volume they occupy, irregular moons are considered one of the most collisionally evolved minor body population in the Solar System. I will talk about our recent survey of the irregular moon system of Saturn. From observations in 2019 we were able to measure the size distribution of the saturnian irregulars and we found that there is a steep slope in the distribution (D^{-4.8}) for moons with diameters from 3 to 4 km. We attributed this steep slope to a recent collision (100s Myr ago) in the saturnian irregular system. Using sparse observations over the following couple of years we were able to discover 55 new moons, for a total of 113 saturnian irregulars. These new discoveries suggest that the recent collision was a catastrophic breakup of a moon with an inclination between 160 and 165 deg.