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Recent work has revealed two classes of Globular Clusters (GCs), dubbedType-I and Type-II. Type-II GCs are characterized by a blue- and a red- redgiant branch composed of stars with different metallicities, often coupled withdistinct abundances in the slow-neutron capture elements (s-elements). Here wecontinue the chemical tagging of Type-II GCs by adding the two least-massiveclusters of this class, NGC1261 and NGC6934. Based on both spectroscopy andphotometry, we find that red stars in NGC1261 are slightly enhanced in [Fe/H]by ~0.1 dex and confirm that red stars of NGC 6934 are enhanced in iron by ~0.2dex. Neither NGC1261 nor NGC6934 show internal variations in the s-elements,which suggests a GC mass threshold for the occurrence of s-process enrichment.We found a significant correlation between the additional Fe locked in the redstars of Type-II GCs and the present-day mass of the cluster. Nevertheless,most Type II GCs retained a small fraction of Fe produced by SNe II, lower thanthe 2%; NGC6273, M54 and omega Centauri are remarkable exceptions. In theappendix, we infer for the first time chemical abundances of Lanthanum, assumedas representative of the s-elements, in M54, the GC located in the nucleus ofthe Sagittarius dwarf galaxy. Red-sequence stars are marginally enhanced in[La/Fe] by 0.10\pm0.06 dex, in contrast with the large [La/Fe] spread of mostType II GCs. We suggest that different processes are responsible for theenrichment in iron and s-elements in Type-II GCs.

Spectroscopy and photometry of the least-massive Type-II globular clusters: NGC1261 AND NGC6934