1:00–1:30 pm
ERC 401 I zinc therefore I am: Zn as a tracer of r-process nucleosynthesis sites in Reticulum II The rapid neutron-capture process is responsible for producing approximately half of the heavy elements in the Universe, yet the astrophysical sites that host this process remain uncertain. To date, the only confirmed candidate sites are neutron-star mergers; yet, galactic chemical evolution models suggest that they alone cannot explain the observed abundances of r-process elements. The extremely metal-poor star DESJ033531-540148 presents a unique opportunity to investigate alternative r-process pathways, namely magnetorotationally driven jet supernovae. This star is a member of the ultra-faint dwarf galaxy Reticulum II, which experienced a rare and prolific r-process event. Its abundance pattern, however, suggests that it formed before such an event and therefore provides a baseline on which theoretical magnetorotationally driven jet supernova yields can be added and compared to observational abundance patterns. We focus in particular on the element Zn, which is produced in magnetorotationally driven jet supernovae but not in neutron-star mergers, as a means to potentially differentiate the two r-process pathways. Here, we present a detailed chemical abundance analysis of DESJ033531-540148 from high-resolution Magellan/MIKE spectroscopy and show that the abundance pattern of this star is consistent with formation prior to the r-process event. We additionally use synthetic spectrum fitting and a profile-likelihood procedure to place a statistically robust 3-sigma upper limit of [Zn/Fe] < 0.66. This work presents the highest S/N Zn abundance constraint for an extremely metal-poor star in an ultra-faint dwarf galaxy, and establishes a promising empirical pathway toward resolving the r-process site question. Advisor: Alex Ji
May
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