An upper limit on the sulphur abundance in HE 1327-2326

Abstract

Context: Star HE 1327-2326 is a unique object, with the lowest measured iron abundance ([Fe/H] ~ -6) and a peculiar chemical composition that includes large overabundances of C, N, and O with respect to iron. One important question is whether the chemical abundances in this star reflect the chemical composition of the gas cloud from which it was formed or if they have been severely affected by other processes, such as dust-gas winnowing. Aims: We measure or provide an upper limit to the abundance of the volatile element sulphur, which can help to discriminate between the two scenarios. Methods: We observed HE 1327-2326 with the high resolution infra-red spectrograph CRIRES at the VLT to observe the S I lines of Multiplet 3 at 1045 nm. Results: We do not detect the S I line. A 3sigma$upper limit on the equivalent width (EW) of any line in our spectrum is EW<0.66 pm. Using either one-dimensional static or three-dimensional hydrodynamical model-atmospheres, this translates into a robust upper limit of [S/H]<-2.6. Conclusions: This upper limit does not provide conclusive evidence for or against dust-gas winnowing, and the evidence coming from other elements (e.g., Na and Ti) is also inconclusive or contradictory. The formation of dust in the atmosphere versus an origin of the metals in a metal-poor supernova with extensive "fall-back" are not mutually exclusive. It is possible that dust formation distorts the peculiar abundance pattern created by a supernova with fall-back, thus the abundance ratios in HE 1327-2326 may be used to constrain the properties of the supernova(e) that produced its metals, but with some caution.

Accepted by Astronomy & Astrophysics Minor typos in the abstract corrected

References in corpus (15)

• Nucleosynthetic signatures of the first stars
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• An extremely primitive halo star
• Fallback and Black Hole Production in Massive Stars
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• HE 1327-2326, an unevolved star with [Fe/H]<-5.0. II. New 3D-1D corrected abundances from a VLT/UVES spectrum
• Sulphur and zinc abundances in Galactic halo stars revisited
• Fallback Supernovae: A Possible Origin of Peculiar Supernovae with Extremely Low Explosion Energies
• New Extremely Metal-Poor Stars in the Galactic Halo
• NLTE determination of the sodium abundance in a homogeneous sample of extremely metal-poor stars
• The chemical compositions of the extreme halo stars HE0107-5240 and HE1327-2326 inferred from 3D hydrodynamical model atmospheres
• The forbidden 1082 nm line of sulphur: the photospheric abundance of sulphur in the Sun and 3D effects
• SPITZER survey of dust grain processing in stable discs around binary post-AGB stars
• Sulphur abundances from the SI near-infrared triplet at 1045 nm
• Could the Ultra Metal-poor Stars be Chemically Peculiar and Not Related to the First Stars?

Cited by in corpus (11)

• Near-Field Cosmology with Metal-Poor Stars
• The Most Metal-Poor Stars. IV. The Two Populations With [Fe/H] < -3.0
• Abundance Profiling of Extremely Metal-Poor Stars and Supernova Properties in the Early Universe
• Stellar Yields of Rotating First Stars. II. Pair Instability Supernovae and Comparison with Observations
• Faint Population III supernovae as the origin of the most iron-poor stars
• Stellar Yields of Rotating First Stars. I. Yields of Weak Supernovae and Abundances of Carbon-enhanced Hyper Metal Poor Stars
• The Gaia-ESO Survey: Galactic evolution of sulphur and zinc
• Chemical Abundance Signature of J0023+0307 -- A Second-Generation Main-Sequence Star with [Fe/H]<-6
• Detection of Phosphorus, Sulphur, and Zinc in the Carbon-Enhanced Metal-Poor Star BD+44 493
• Fingerprint of the first stars: multi-enriched extremely metal-poor stars in the TOPoS survey
• Searching for Dust around Hyper Metal-Poor Stars