Doctor of Philosophy
Date of Defense
Knowledge of the initial conditions present in the early solar nebula is required to understand the evolution and its current volatile content. Comets were some of the first objects to accrete in the solar nebula. They are among the most pristine (primitive) remnants of the solar system formation, and their present-day volatile composition likely reflects the composition and conditions where (and when) they formed. Therefore, they are fossils of the solar system formation. High-resolution near-infrared spectroscopy is a valuable tool for sampling the parent volatile (i.e., ices subliming directly from the nucleus) composition of comets via analysis of fluorescence emission in cometary comae.
An overall goal of comet volatile composition studies is determining whether comets can be classified based on their volatile content and what this reveals about the history of the early solar system. Early work produced encouraging results, but recent work has left questions regarding whether a compositional taxonomy based on near-infrared measurements is feasible. These include questions such as: Are observed systematic compositional differences between Jupiter-family comets and Oort cloud comets the result of evolutionary effects or reflective of formative conditions? Is temporal variability in coma composition a common phenomenon, and if so, how can present-day measurements be related to natal solar system conditions? Can we place comet volatile compositions in a meaningful context? In this work we examine these questions in the context of near-infrared measurements of Oort cloud comets and Jupiter-family comets, as well as a comparison between our results and extensive results from the Rosetta mission to comet 67P/Churyumov–Gerasimenko.
Saki, Mohammad, "Analysis of the Primary Volatile Compositions in the Oort Cloud and Jupiter-family Comets Towards the Goal of Understanding Their Origin and Diversity" (2021). Dissertations. 1095.