Kavli Affiliate: Alexander P. Ji
| First 5 Authors: Sam A. Usman, Alexander P. Ji, Ting S. Li, Andrew B. Pace, Lara R. Cullinane
| Summary:
Milky Way globular clusters (GCs) display chemical enrichment in a phenomenon
called multiple stellar populations (MSPs). While the enrichment mechanism is
not fully understood, there is a correlation between a cluster’s mass and the
fraction of enriched stars found therein. However, present-day GC masses are
often smaller than their masses at the time of formation due to dynamical mass
loss. In this work, we explore the relationship between mass and MSPs using the
stellar stream 300S. We present the chemical abundances of eight red giant
branch member stars in 300S with high-resolution spectroscopy from
Magellan/MIKE. We identify one enriched star characteristic of MSPs and no
detectable metallicity dispersion, confirming that the progenitor of 300S was a
globular cluster. The fraction of enriched stars (12.5%) observed in our 300S
stars is less than the 50% of stars found enriched in Milky Way GCs of
comparable present-day mass ($sim10^{4.5}$msun). We calculate the mass of
300S’s progenitor and compare it to the initial masses of intact GCs, finding
that 300S aligns well with the trend between the system mass at formation and
enrichment. 300S’s progenitor may straddle the critical mass threshold for the
formation of MSPs and can therefore serve as a benchmark for the stellar
enrichment process. Additionally, we identify a CH star, with high abundances
of textit{s}-process elements, probably accreted from a binary companion. The
rarity of such binaries in intact GCs may imply stellar streams permit the
survival of binaries that would otherwise be disrupted.
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