  context : Unlike silicon and calcium, sulphur is an alpha-element which does
not form dust. Some of the available observations of the evolution of sulphur
with metallicity indicate an increased scatter of sulphur to iron ratios at low
metallicities or even a bimodal distribution, with some stars showing constant
S/Fe at all metallicities and others showing an increasing S/Fe ratio with
decreasing metallicity. In metal-poor stars SI lines of Multiplet 1 at 920 nm
are not yet too weak to permit to measure the sulphur abundance A(S), however
in ground-based observations they are severely affected by telluric lines. aims
: We investigate the possibility to measure sulphur abundances from SI Mult. 3
at 1045 nm lines, which lie in the near infra-red. These are slightly weaker
than those of Mult. 1, but lie in a range not affected by telluric lines.
method We investigate the lines of Mult.3 in the Sun (G2V), Procyon (F5V), HD
33256 (F5V), HD 25069 (G9V) and epsilon Eri (HD 22049, K2V). For the Sun and
Procyon the analysis has been performed with CO5BOLD 3D hydrodynamical model
atmospheres, for the other three stars, for which hydrodynamical simulations
are not available, the analysis has been performed using 1D model atmospheres.
results For our sample of stars we find a global agreement of A(S) from lines
of different multiplets. conclusions : Our results suggest that the infrared
lines of Mult. 3 are a viable indicator of the sulphur abundance which, because
of the intrinsic strength of this multiplet, should be suitable to study the
trend of [S/Fe] at low metallicities.
