NGC6362: the least massive globular cluster with chemically distinct
  multiple populations
  We present the first measure of Fe and Na abundances in NGC 6362, a low-mass
globular cluster where first and second generation stars are fully spatially
mixed. A total of 160 member stars (along the red giant branch and the red
horizontal branch) have been observed with the multi-object spectrograph FLAMES
at the Very Large Telescope. We find that the cluster has an iron abundance of
[Fe/H]=--1.09$\pm$0.01 dex, without evidence of intrinsic dispersion. On the
other hand, the [Na/Fe] distribution turns out to be intrinsically broad and
bimodal. The Na-poor and Na-rich stars populate, respectively, the bluest and
the reddest red giant branches detected in the color-magnitude diagrams
including the U filter. The red giant branch is composed of a mixture of first
and second generation stars in a similar proportion, while almost all the red
horizontal branch stars belong to the first cluster generation. Until now, NGC
6362 is the least massive globular cluster where both the photometric and
spectroscopic signatures of multiple populations have been detected.
