Research Interests

Deriving/constraining the nucleosynthetic sites and yields of neutron-capture elements from CARDs

Another fundamental question in Galactic archeology is: what is the precise origin (nucleosynthetic site(s)) of the elements? For observers, this amounts to an investigative search for stars with tell-tale signs of enrichment that reflect an unique theorize site of origin ((super) AGB stars, core-collapse SN, Type Ia SN, neutron star mergers (NSMs)). This question can be addressed, in part, by semi-analytic statistical modeling of dwarf galaxies if one assumes that the nucleosynthetic origins of stars (esp. very metal poor (VMP) stars) in the MW halo are the same as those found in dwarf galaxies. In particular, the ultra-faint dwarf (UFD) galaxies represent systems that are likely or approx. "one-shot" galaxies --- that is, galaxies that only underwent ~2-3 episodes (generations) of star formation in their star formation histories (SFHs). Assuming this is "true", one can generate statistical distributions for chemical abundance ratios of various elements in UFDs and compare them to VMP MW halo stars to derive likely mass-dependent yield "strengths" for elements like Barium and Strontium (vs. e.g., those of alpha-elements). Using this technique can help identify and constrain the occurrence rate of various nucleosynthetic processes/events.

One core aim of my research is to develop CARD-tracking semi-analytic models (SAM) to address this question by developing models that can reliably emulate both UFD and classical dwarf galactic chemical evolution (i.e. reproduce both "one-shot" and multi-generational SFHs). This would allow for a consistent analysis of possible nucleosynthetic origins across a robust mass range of galactic systems.

See here for details.

Duane M. Lee