Sulphur abundances in halo stars from Multiplet 3 at 1045 nm

Abstract

Sulphur is a volatile alpha-element which is not locked into dust grains in the interstellar medium (ISM). Hence, its abundance does not need to be corrected for dust depletion when comparing the ISM to the stellar atmospheres. The abundance of sulphur in the photosphere of metal-poor stars is a matter of debate: according to some authors, [S/Fe] versus [Fe/H] forms a plateau at low metallicity, while, according to other studies, there is a large scatter or perhaps a bimodal distribution. In metal-poor stars sulphur is detectable by its lines of Mult.1 at 920 nm, but this range is heavily contaminated by telluric absorptions, and one line of the multiplet is blended by the hydrogen Paschen zeta line. We study the possibility of using Mult. 3 (at 1045 nm) for deriving the sulphur abundance because this range, now observable at the VLT with the infra-red spectrograph CRIRES, is little contaminated by telluric absorption and not affected by blends at least in metal-poor stars. We compare the abundances derived from Multiplets 1 and 3, taking into account NLTE corrections and 3D effects. Here we present the results for a sample of four stars, although the scatter is less pronounced than in previous analysis, we cannot find a plateau in [S/Fe], and confirm the scatter of the sulphur abundance at low metallicity.

to be published in Astronomische Nachrichten

References in corpus (5)

• Sulphur and zinc abundances in Galactic halo stars revisited
• Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg] and [K/Mg] in the Milky Way
• The forbidden 1082 nm line of sulphur: the photospheric abundance of sulphur in the Sun and 3D effects
• Sulphur abundances from the SI near-infrared triplet at 1045 nm
• Sulphur abundances in disk stars as determined from the forbidden 10821 A [SI] line

Cited by in corpus (12)

• Simulations of stellar convection with CO5BOLD
• The Gaia-ESO Survey: Galactic evolution of sulphur and zinc
• Detection of Neutral Phosphorus in the Near Ultraviolet Spectra of Late-Type Stars
• Sulphur in the Sculptor dwarf spheroidal galaxy - Including NLTE corrections
• Exploring the [S/Fe] Behavior of Metal-Poor Stars with the S I 1.046 micron Lines
• Sulphur abundances in halo giants from the [S I] line at 1082 nm and the S I triplet around 1045 nm
• The Galactic evolution of sulphur as traced by globular clusters
• An upper limit on the sulphur abundance in HE 1327-2326
• Clues on the Galactic evolution of sulphur from star clusters
• Sulfur abundances in three Galactic clusters: Ruprecht 106, Trumpler 5 and Trumpler 20
• MINCE III. Detailed chemical analysis of the UVES sample
• On the Galactic chemical evolution of sulphur. Sulphur abundances from the [S i] 1082 nm line in giants