Research Division Seminar
Tracing the Origin and Evolution of Halo Stars and Globular Clusters: Insights from the R-Process Alliance

Abstract

Understanding the abundance patterns of metal-poor stars and the production of heavy elements through various nucleosynthesis processes offers crucial insights into the chemical evolution of the Milky Way. We investigate the origins of light, alpha, Fe-peak, and r-process elements in metal-poor halo stars using data from the R-Process Alliance observed by the Gran Telescopio Canarias (GTC). Our analysis of these faint stars reveals intriguing patterns. We utilize the abundances of carbon, Fe-peak elements and the alpha-elements to probe the contributions from different nucleosynthesis channels in the progenitor supernovae. Additionally, we identify globular cluster stars at very low metallicity, which adds to the growing evidence of a lower metallicity floor for GCs. We also reveal differences in the trends of the neutron-capture element abundances from the RPA data releases, which provide constraints on their nucleosynthesis sites and subsequent evolution. Complementing this, we use early data from the new dual-fibre high-resolution spectrograph GHOST at Gemini South to study globular clusters. We identify first and second-generation stars in the metal-poor globular cluster NGC 2298 through light element anti-correlation, obtaining precise abundances for over 45 elements, including 20 neutron-capture elements up to thorium. A larger dispersion in n-capture and Fe-peak elements is observed among first-generation stars, along with variations in the universal r-process pattern. Increases in Sr and Ba with Mg, significant trends in light, alpha, and Fe-peak abundances, and correlations between light and r-process abundances are noted. These findings enhance our understanding of the Milky Way's chemical evolution by integrating data on metal-poor stars and globular clusters, elucidating the nucleosynthetic pathways shaping our Galaxy's elemental composition.