Presentation #426.07 in the session Stellar Populations and Evolution II.
Phosphorus is a key element for life on Earth and is thought to be created in different nucleosynthesis channels, however few precise stellar P abundances exist. The 150 known P abundances do not match chemical evolution models and the most significant sites of P nucleosynthesis are unclear. To understand the chemical evolution of P in the Milky Way and to constrain models of P production, we have measured P abundances in 163 stars using observations from the Habitable-zone Planet Finder on the Hobby-Eberly telescope. By comparing P to abundances of alpha-elements, iron peak elements, and s-process elements, we find evidence that P is made in core collapse supernovae and not significantly produced in delayed nucleosynthesis events (e.g., Type Ia supernovae). A difference in [P/Fe] ratios was also found between thin and thick disk stars that were classified with kinematics. Finally, we find no chemical evolution models can completely reproduce the evolution of P for stars between -1 < [Fe/H] < 0.