Sampling the Evolution of Solar System Cometoids

Citation

Zhang, Qicheng (2024) Sampling the Evolution of Solar System Cometoids. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/mjje-pc39. https://resolver.caltech.edu/CaltechTHESIS:01012024-070706394

Abstract

Comets are commonly defined to be planetesimals visibly losing mass through volatile sublimation. In the solar system, such behavior characterizes but a brief stage in the overall evolution of these objects, as limited by their supply of accessible volatile materials and the often short dynamical lifetimes of orbits sufficiently near the Sun for said volatiles to actually volatilize. In this thesis, I explore the characteristics of several different types of ``cometoids''---planetesimals visibly exhibiting comet-like mass loss sometime in their recent past, present, or near future---in both the outer and inner solar system at different stages in their physical and dynamical evolution. I first use stellar occultations---or rather, the lack thereof detected---to constrain their abundance of kilometer-scale objects in the Kuiper Belt, from which many comets are sourced. I then evaluate how the optical brightness, color, and polarization of dust ejected by a classical, currently active comet changes when exposed to the space environment in order to probe the material properties of its nucleus. Finally, I investigate an otherwise ordinary but active asteroid to explore how intense solar heating as it passes very near the Sun can volatilize its rocky surface to produce bright sodium emission explaining its comet-like behavior.

Thesis Files