We present the abundance analysis of 82 red giant branch stars in the dense , metal-poor globular cluster NGC 6093 ( M 80 ) , the largest sample of stars analyzed in this way for this cluster .
From high resolution UVES spectra of 14 stars and intermediate resolution GIRAFFE spectra for the other stars we derived abundances of O , Na , Mg , Al , Si , Ca , Sc , Ti , V , Cr , Mn , Fe , Co , Ni , Cu , Zn , Y , Zr , Ba , La , Ce , Pr , Nd , Sm , Eu .
On our UVES metallicity scale the mean metal abundance of M 80 is [ Fe/H ] = -1.791 \pm 0.006 \pm 0.076 ( \pm statistical \pm systematic error ) with \sigma = 0.023 ( 14 stars ) .
M 80 shows star to star variations in proton-capture elements , and the extension of the Na-O anticorrelation perfectly fit the relations with ( i ) total cluster mass , ( ii ) horizontal branch morphology , and ( iii ) cluster concentration previously found by our group .
The chemistry of multiple stellar populations in M 80 does not look extreme .
The cluster is also a typical representative of halo globular clusters for what concerns the pattern of \alpha - capture and Fe-group elements .
However we found that a significant contribution from the s - process is required to account for the distribution of neutron-capture elements .
A minority of stars in M 80 seem to exhibit slightly enhanced abundances of s - process species , compatible with those observed in M 22 and NGC 1851 , although further confirmation from larger samples is required .