EDP Sciences
Free access
Volume 443, Number 3, December I 2005
Page(s) 1029 - 1032
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20053569

A&A 443, 1029-1032 (2005)
DOI: 10.1051/0004-6361:20053569

Sulphur abundances in metal-poor stars

A. J. Korn and N. Ryde

Department of Astronomy and Space Physics, Box 515, 75 120 Uppsala, Sweden
    e-mail: [korn;ryde]@astro.uu.se

(Received 3 June 2005 / Accepted 12 September 2005 )

We investigate the debated "sulphur discrepancy" found among metal-poor stars of the Galactic halo with [Fe/H] < -2. This discrepancy stems in part from the use of two different sets of sulphur lines, the very weak triplet at 8694-95 Å and the stronger triplet lines at 9212-9238 Å. For three representative cases of metal-poor dwarf, turnoff and subgiant stars, we argue that the abundances from the $\lambda\lambda$8694-95 lines have been overestimated which has led to a continually rising trend of [S/Fe] as metallicity decreases. Given that the near-IR region is subject to CCD fringing, these weak lines become excessively difficult to measure accurately in the metallicity regime of [Fe/H] < -2. Based on homogeneously determined spectroscopic stellar parameters, we also present updated [S/Fe] ratios from the $\lambda\lambda$9212-9238 lines which suggest a plateau-like behaviour similar to that seen for other alpha elements.

Key words: stars: abundances -- stars: atmospheres -- stars: Population II -- Galaxy: abundances -- Galaxy: evolution -- Galaxy: halo

SIMBAD Objects

© ESO 2005