Evidence for multiple populations in the intermediate age cluster
  Lindsay 1 in the SMC
  Lindsay 1 is an intermediate age (approx 8 Gyr) massive cluster in the Small
Magellanic Cloud (SMC). Using VLT FORS2 spectra of 16 probable cluster members
on the lower RGB of the cluster, we measure CN and CH band strengths (at 3883
and 4300 Angstroms respectively), along with carbon and nitrogen abundances and
find that a sub-population of stars has significant nitrogen enrichment. A lack
of spread in carbon abundances excludes evolutionary mixing as the source of
this enrichment, so we conclude that this is evidence of multiple populations.
Therefore, L1 is the youngest cluster to show such variations, implying that
the process triggering the onset of multiple populations must operate until at
least redshift ~1.
