Surface Characterization of Hydrated Planetesimals inthe Main Asteroid Belt

As one of the most thermally stable solvents, water is critical to grasping the material evolution of planetary systems. Ch-type asteroids show clear signs of water on their surfaces, anticipated to serve as a local water reservoir in today’s main asteroid belt region and also as the parent bodies of CM meteorites that are presumably the primary water source on early Earth. Aside from the composition of their building blocks, little is known about the physical makeup of dust particles, which is related to environmental information before they settled in their current orbits. Observations revealed polarimetric differences in Ch-type asteroids in the optical, indicating potential dust gradients among the bodies. In this presentation, we will report interim results we obtained from our new optical multi-band photometric and near-infrared polarimetric observations of large (>~80 km in diameter) Ch-type main-belt asteroids and discuss what insights we have gained into constraining the evolution of the bodies.