Kron 3: a fourth intermediate age cluster in the SMC with evidence of
  multiple populations
  We present the results of a spectroscopic study of the intermediate age
(approximately 6.5 Gyr) massive cluster Kron 3 in the Small Magellanic Cloud.
We measure CN and CH band strengths (at 3839 and 4300 Angstroms respectively)
using VLT FORS2 spectra of 16 cluster members and find a sub-population of 5
stars enriched in nitrogen. We conclude that this is evidence for multiple
populations in Kron 3, the fourth intermediate age cluster, after Lindsay 1,
NGC 416 and NGC 339 (ages 6-8 Gyr), to display this phenomenon originally
thought to be a unique characteristic of old globular clusters. At 6.5 Gyr this
is one of the youngest clusters with multiple populations, indicating that the
mechanism responsible for their onset must operate until a redshift of at least
0.75, much later than the peak of globular cluster formation at redshift ~3.
