Multiple populations and a CH star found in the 300S globular cluster stellar stream

Sam A. Usman*, Alexander P. Ji, Ting S. Li, Andrew B. Pace, Lara R. Cullinane, Gary S. Da Costa, Sergey E. Koposov, Geraint F. Lewis, Daniel B. Zucker, Vasily Belokurov, Joss Bland-Hawthorn, Peter S. Ferguson, Terese T. Hansen, Guilherme Limberg, Sarah L. Martell, Madeleine McKenzie, Joshua D. Simon, S5 Collaboration

*Corresponding author for this work

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Abstract

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. Ho we ver, 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 GC. The fraction of enriched stars (12.5 per cent) observed in our 300S stars is less than the 50 per cent of stars found enriched in Milky Way GCs of comparable present-day mass ( ∼104.5M). 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 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.

Original languageEnglish
Pages (from-to)2413-2427
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume529
Issue number3
DOIs
Publication statusPublished - 1 Apr 2024

Bibliographical note

© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • nuclear reactions, nucleosynthesis, abundances
  • stars: abundances
  • Galaxy: halo
  • Galaxy: kinematics and dynamics
  • Local Group
  • Galaxy: globular clusters: general

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