Speaker
Description
Observational studies focusing on low- to intermediate-mass evolved stars, such as post-AGB stars, reveal remarkable diversity in their chemical compositions, particularly in terms of CNO abundance and s-process enrichment. These stars provide critical insights into AGB nucleosynthesis, dredge-up events, and hot-bottom burning. However, the mechanisms driving the observed diversity in their chemical signatures remain uncertain.
In this talk, I will explore both observational and modelling perspectives on s-process and carbon-enriched post-AGB stars. I will also discuss our recent discovery of the most carbon-rich and s-process enhanced post-AGB star in the Small Magellanic Cloud (SMC). High-resolution optical spectroscopy with VLT/UVES has revealed this star's exceptionally high C/O ratio and a significant enhancement of s-process elements, including the first-ever precise measurement of lead (Pb) abundance, the final product of the s-process nucleosynthesis. These results challenge existing nucleosynthesis models and set a new benchmark for understanding how mass loss rates and mixing processes shape the chemical evolution of evolved stars.
