Sulphur abundances from the S i near-infrared triplet at 1045 nm

Context.Unlike silicon and calcium, sulphur is an α-element that 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 S i lines of Multiplet 1 at 920 nm are not yet too weak to permit the measurement of the sulphur abundance A(S); however, in ground-based observations they are severely affected by telluric lines.

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