ESO 452−SC11: the lowest mass globular cluster with a potential chemical inhomogeneity

2017/08/23 by Jeffrey D. Simpson, Gayandhi De Silva, Sarah L. Martell +3
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Astrophysics and Star Formation Studies #Cluster (spacecraft) #Globular cluster #Low Mass #Milky Way #Open cluster #Physics #Star cluster #Star formation #Stars #Stellar mass #Stellar population #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR

paper · pdf · doi:10.1093/mnras/stx2174

13 pages, 11 figures. Accepted for publication in MNRAS

arxiv created 2017/08/23 · openalex publication_date 2017/08/24 · openalex created_date 2017/08/31 · arxiv updated 2017/10/11 · openalex updated_date 2026/08/06

Abstract

We present the largest spectroscopic investigation of one of the faintest and least studied stellar clusters of the Milky Way, ESO452-SC11. Using the Anglo-Australian Telescope AAOmega and Keck HIRES spectrographs we have identified 11 members of the cluster and found indications of star-to-star light element abundance variation, primarily using the blue cyanogen (CN) absorption features. From a stellar density profile, we estimate a total cluster mass of (6.8±3.4)×10³ solar masses. This would make ESO452-SC11 the lowest mass cluster with evidence for multiple populations. These data were also used to measure the radial velocity of the cluster (16.7±0.3 km s^-1) and confirm that ESO452-SC11 is relatively metal-rich for a globular cluster ([Fe/H]=-0.81±0.13). All known massive clusters studied in detail show multiple populations of stars each with a different chemical composition, but many low-mass globular clusters appear to be chemically homogeneous. ESO452-SC11 sets a lower mass limit for the multiple stellar population phenomenon.

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