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 \pm 3.4 ) \times 10 ^ { 3 } M _ { \textrm { \sun } } .
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 \pm 0.3 km s ^ { -1 } ) and confirm that ESO452-SC11 is relatively metal-rich for a globular cluster ( [ \textrm { Fe } / \textrm { H } ] = -0.81 \pm 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 .