The Galactic evolution of sulphur as traced by globular clusters
arXiv:1503.02691 · doi:10.1051/0004-6361/201425058
Abstract
Sulphur is an important, volatile alpha element but its role in the Galactic chemical evolution is still uncertain. We derive the S abundances in RGB stars in three Galactic globular clusters (GC) that cover a wide metallicity range (-2.3<[Fe/H]<-1.2), namely M4, M22, and M30. The halo field stars show a large scatter in the [S/Fe] ratio in this metallicity span, which is inconsistent with canonical chemical evolution models. To date, very few measurements of [S/Fe] exist for stars in GCs, which are good tracers of the chemical enrichment of their environment. However, some light and alpha elements show star-to-star variations within individual GCs and it is yet unclear whether sulphur also varies between GC stars. We used the the infrared spectrograph CRIRES to obtain high-resolution (R~50000), high signal-to-noise (SNR~200 per px) spectra in the region of the S I multiplet 3 at 1045 nm for 15 GC stars selected from the literature (6 stars in M4, 6 stars in M22 and 3 stars in M30). Multiplet 3 is better suited for S abundance derivation than the more commonly used lines of multiplet 1 at 920 nm, since its lines are not blended by telluric absorption or other stellar features at low metallicity. We used spectral synthesis to derive the [S/Fe] ratio of the stars assuming local thermodynamic equilibrium (LTE). We find mean [S/Fe] = 0.58 +/- 0.01 +/- 0.20 dex (statistical and systematic error) for M4, [S/Fe] = 0.57+/-0.01+/-0.19 dex for M22, and [S/Fe] = 0.55+/-0.02+/-0.16 dex for M30. The negative NLTE corrections are estimated to be in the order of the systematic uncertainties. With the tentative exception of two stars with measured high S abundances, we conclude that sulphur behaves like a typical alpha element in the studied Galactic GCs, showing enhanced abundances with respect to the solar value at metallicities below [Fe/H] = -1.0 dex without a considerable spread.
arXiv comment9 pages, 7 figures, accepted for publication in A&A
References in corpus (39)
- A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
- Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
- Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
- Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
- Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
- Stellar Chemical Signatures And Hierarchical Galaxy Formation
- Na-O Anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra
- Abundance Patterns in the Draco, Sextans and Ursa Minor Dwarf Spheroidal Galaxies
- VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: I. Nucleosynthesis and Abundance Ratios
- Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
- Abundances for metal-poor stars with accurate parallaxes I. Basic data
- Evolution, Explosion and Nucleosynthesis of Core Collapse Supernovae
- The two metallicity groups of the globular cluster M22: a chemical perspective
- 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
- Chemistry of the Sagittarius Dwarf Galaxy: a Top-Light IMF, Outflows and the R-Process
- Sulphur and zinc abundances in Galactic halo stars revisited
- A double stellar generation in the Globular Cluster NGC6656 (M 22). Two stellar groups with different iron and s-process element abundance
- Elemental abundances in the atmosphere of clump giants
- M22: A [Fe/H] Abundance Range Revealed
- Sulphur and zinc abundances in Galactic stars and damped Lyman-alpha systems
- Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
- The forbidden 1082 nm line of sulphur: the photospheric abundance of sulphur in the Sun and 3D effects
- Lithium and sodium in the globular cluster M4. Detection of a Li-rich dwarf star: preservation or pollution?
- Sulphur abundance in Galactic stars
- Study of the Galactic Interstellar Medium from High Resolution X-Ray Spectroscopy: X-Ray Absorption Fine Structure and Abundances of O, Mg, Si, S, and Fe
- The metal-poor Knee in the Fornax Dwarf Spheroidal Galaxy
- Chemical Evolution of Damped Ly alpha galaxies: The [S/Zn] abundance ratio at redshift z > 2
- A Comparison of Absorption and Emission Line Abundances in the Nearby Damped Lyman-alpha Galaxy SBS 1543+593
- First Stars XIV. Sulfur abundances in extremely metal-poor (EMP) stars
- Sulphur abundances from the SI near-infrared triplet at 1045 nm
- CRIRES-POP: A library of high resolution spectra in the near-infrared
- 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
- Sulphur abundances in halo stars from Multiplet 3 at 1045 nm
- Clues on the Galactic evolution of sulphur from star clusters
- Sulphur abundances in Terzan 7
- Sulphur in the Globular Clusters 47 Tucanae and NGC 6752
- Sulphur in the metal poor globular cluster NGC 6397
- Behavior of [S/Fe] in Very Metal-Poor Stars from the S I 1.046 micron Lines Revisited
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- Sulfur abundances in three Galactic clusters: Ruprecht 106, Trumpler 5 and Trumpler 20
- Influence of departures from LTE on determinations of the sulfur abundances in A-K type stars