In Galactic halo stars , sulphur has been shown to behave like other \alpha -elements , but until now , no comprehensive studies have been done on this element in stars of other galaxies .
Here , we use high-resolution ESO VLT/FLAMES/GIRAFFE spectra to determine sulphur abundances for 85 stars in the Sculptor dwarf spheroidal galaxy , covering the metallicity range -2.5 \leq \text { [ Fe / H ] } \leq - 0.8 .
The abundances are derived from the S I triplet at 9213 , 9228 , and 9238 Å .
These lines have been shown to be sensitive to departure from local thermodynamic equilibrium , i.e .
NLTE effects .
Therefore , we present new NLTE corrections for a grid of stellar parameters covering those of the target stars .
The NLTE-corrected sulphur abundances in Sculptor show the same behaviour as other \alpha -elements in that galaxy ( such as Mg , Si , and Ca ) .
At lower metallicities ( \text { [ Fe / H ] } \lesssim - 2 ) the abundances are consistent with a plateau at \text { [ S / Fe ] } \approx + 0.16 , similar to what is observed in the Galactic halo , \text { [ S / Fe ] } \approx + 0.2 .
With increasing [ Fe/H ] , the [ S/Fe ] ratio declines , reaching negative values at \text { [ Fe / H ] } \gtrsim - 1.5 .
The sample also shows an increase in [ S/Mg ] with [ Fe/H ] , most probably because of enrichment from Type Ia supernovae .