Abstract

Chlorine (Cl) and phosphorus (P) are thought to be produced in a variety of nucleosynthesis events, including in core collapse supernovae and AGB stars, yet measurements of these elements in stars needed to confirm these production sites are scarce. I will discuss our results from Galactic chemical evolution studies of Cl and P using abundance measurements from HCl lines at 3.7 microns and P lines at 1.06 microns. Using a sample of 52 cool giants, we found that Cl is consistent with chemical evolution models over -0.6 < [Fe/H] < 0.2 . In addition, we measured the Cl isotope ratio in seven M giants and found a significant scatter in the small sample, similar to what is observed in the ISM. While our Cl measurements are consistent with chemical evolution models, the same models under-produce P compared to observations. We also find that ratios of P to Si and Mg suggest that P is produced primarily in core collapse supernovae. Finally, I will discuss future studies of Cl in carbon stars and additional observations to increase the number of P measurements.