Chemical Elements as Tracers of the Evolution of the Milky Way

Womack, Kate

Abstract

To better understand the processes that have formed the Milky Way and enriched the galactic gas, we can study galactic chemical evolution (GCE). When we study GCE we combine our understanding of galaxy formation with stellar evolution to trace the chemical composition of the galactic gas. Using the semi-analytical GCE codes OMEGA and OMEGA+ to study the evolution of the Milky Way interstellar medium (ISM), we first perform two single element studies investigating the evolution of fluorine and phosphorus abundances. Second, we develop OMEGA to study the evolution of abundance gradients in the Milky Way with both time and radius, using a sample of open clusters in the galactic disc.
The origins of fluorine are investigated by employing a variety of yield sets in our chemical evolution models. We find rotating massive stars are important to reproduce observations, while also ruling out Wolf-Rayet winds as a dominant source of galactic fluorine. We use a similar technique to try to determine the origins of a sample of phosphorus-rich stars. Again, we use a range of yield sets, in this case focussing on massive stars. We are not able to reproduce the full abundance trends of the P-rich sample with any of the models, pointing to the presence of additional physical processes, which are discussed in this Thesis.
We move on to develop a multi-zone version of OMEGA, known as ALPHA. Using ALPHA we develop two Milky Way models, one model includes radial gas flows and the other does not. We go on to use these models to study some chemical clock ratios found in the literature, especially considering [s/𝛼] ratios. We find we can go some way to qualitatively reproducing the abundance gradient trends seen in open clusters. We use the models to show the predictive power of chemical evolution modelling.

Citation

Womack, K. (2025). Chemical Elements as Tracers of the Evolution of the Milky Way. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/5086887

• Thesis Type: Thesis
• Deposit Date: Mar 21, 2025
• Publicly Available Date: Apr 11, 2025
• Keywords: Physics
• Public URL: https://hull-repository.worktribe.com/output/5086887
• Additional Information: Physics; School of Natural Sciences; University of Hull
• Award Date: Jan 7, 2025