Chemical abundances of 1111 FGK stars from the HARPS-GTO planet search
  sample. III. Sulfur
  Context. Elemental abundances are of prime importance to help us reconstruct
the origin and evolution of stars and galaxies in our Universe. Sulfur
abundances have not been as heavily studied as other elements, so some details
regarding its behaviour are still unclear. Aims. We aim to investigate [S/Fe]
ratios in stars of the solar neighbourhood in order to analyse the chemical
evolution of sulfur and probe for possible differences in abundances of planet
host and non-planet host stars. Methods. We use the code MOOG to perform
spectral synthesis and derive v*sin(i) values and [S/Fe] ratios for 719 FGK
stars with high-resolution (R~115000) and high-quality spectra from the
HARPS-GTO program. We find the best fit and corresponding parameter values by
performing chi-square minimisation of the deviation between synthetic profiles
and observational spectra. Results. Our results reveal that sulfur behaves as a
typical alpha-element, with low abundances in young thin disk stars and high
abundances in old thick disk stars, following what was expected from our
understanding of the Galactic chemical evolution (GCE). Nevertheless, further
studies into the abundances of sulfur in very metal-poor stars are required as
our sample only derived sulfur abundances to stars with metallicity as low as
[Fe/H]=-1.13 dex. High-alpha metal rich stars are more enhanced in sulfur
compared to their thin disk counterparts at the same metallicity. We compare
our results to GCE models from other authors in the [S/Fe] vs. [Fe/H] plane.
The [S/Fe]-age relationship is a good proxy for time, just like it is the case
with other alpha-elements. We report no differences in the abundances of sulfur
between stars with and without planetary companions in the metallicity range
[Fe/H] >= -0.3 dex.
