Rare Elements from the First Stars to Today

​Understanding the origin of the elements is one of the major challenges of modern astrophysics. Elements along the bottom two-thirds of the periodic table — including arsenic, selenium, barium, europium, lead, thorium, uranium, and others — are mainly produced by neutron-capture reactions. Some had not been detected previously in late-type stars, and the origins of all are not fully understood at present. My work focuses on abundances derived from ultraviolet and optical high-resolution spectroscopic data of dwarf galaxies, globular clusters, and field stars in the stellar halo. I will present recent observations of these elements that successfully muddy our understanding of when and how they were first produced in the early Universe.