We present the largest spectroscopic investigation of one of the faintest and least studied stellar clusters of the MilkyWay, ESO 452-SC11. Using the Anglo-Australian Telescope AAOmega and Keck High Resolution Echelle Spectrometer 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 absorption features. From a stellar density profile, we estimate a total cluster mass of (6.8 +/- 3.4) x 10³M⊙. This would make ESO 452-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 kms¯¹) and confirm that ESO 452-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. ESO 452-SC11 sets a lower mass limit for the multiple stellar population phenomenon.
Bibliographical noteThis article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, 472(3), pp.2856–2868. The original publication is available at https://doi.org/10.1093/mnras/stx2174. Copyright 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
- globular clusters: individual: ESO 452-SC11