Based on observations collected at the European Southern Observatory at Paranal, Chile (programmes No. 67.D-0106, 73.D-0024 and CRIRES science verification program 60.A-9072).

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Table 1 and Appendices are only available in electronic form at http://www.aanda.org

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... CDS

http://cdsweb.u-strasbg.fr/cgi-bin/qcat?/A+A/415/993

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...Å

The UVES spectra also cover the 1.046 ${\mu }$ m S I triplet but due to the low efficiency of the MIT CCD at this wavelength, the quality is far too low (S/N < 25) for a precise determination of the sulphur abundance.

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... $-3.2 < \mbox{\rm [Fe/H]}< -2$

This range is on our metallicity scale. The metallicities of Arnone et al. (2005) are based on Fe I lines and a $T_{\rm eff}$ scale that is on the average $\sim$ 200 K lower than our scale. For 14 stars in common with our sample, they get [Fe/H] values that are on the average 0.20 dex lower than our values.

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