Sulfur abundances in three Galactic clusters: Ruprecht 106, Trumpler 5 and Trumpler 20

Abstract

Context. Sulfur (S) is one of the lesser-studied $\alpha$-elements. Published investigations of its behavior have so far focused on local stars, and only a few clusters of the Milky Way have been considered to study this topic. We aim to study the S content of the globular cluster Ruprecht 106 -- which has never before been studied for this purpose, but is known to present low levels of the [$\alpha$/Fe] abundance ratio -- and the open cluster Trumpler 5. The only star studied so far in Trumpler 5 shows an unexpectedly low abundance of S. Aims. With this work, we aim to provide the first S abundance in Ruprecht 106 and to investigate the S content of Trumpler 5 with a larger sample of stars. The open cluster Trumpler 20 is considered as a reference object. Methods. We performed a standard abundance analysis based on 1D model atmospheres in local thermodynamical equilibrium (LTE) and on high-resolution and high-signal-to-noise-ratio UVES-slit and UVES/FLAMES spectra. We also applied corrections for nonLTE. The metallicities of the targets were obtained by studying equivalent widths. Sulfur abundances were derived from multiplets 1, 6, and 8 by spectrosynthesis. Results. We find that the metallicities of Ruprecht 106 and Trumpler 5 are [Fe/H]= -1.37+/-0.11 and [Fe/H]= -0.49+/-0.14, respectively. Ruprecht 106 is less S-rich than the other Galactic clusters at similar metallicity. The low S content of Ruprecht 106, [S/Fe]NLTE= -0.52+/-0.13, is consistent with its shortage of $\alpha$-elements. This supports an extra-galactic origin of this cluster. We obtained a new and more robust S content value of Trumpler 5 of about [S/Fe]NLTE= 0.05+/-0.20. According to our results, Trumpler 5 follows the trend of the Galactic disk in the [S/Fe]LTE versus [Fe/H] diagram. Our results for Trumpler 20, of namely [Fe/H]= 0.06+/-0.15 and [S/Fe]NLTE= -0.28+/-0.21, are in agreement with those in the literature.

arXiv comment15 pages, 7 figures, 5 tables

References in corpus (60)

• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• New catalogue of optically visible open clusters and candidates
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• Gaia Early Data Release 3: Photometric content and validation
• Painting a portrait of the Galactic disc with its stellar clusters
• The Ages of 55 Globular Clusters as Determined Using an Improved delta V_TO^HB Method Along with Color-Magnitude Diagram Constraints, and Their Implications for Broader Issues
• Origin of the system of globular clusters in the Milky Way
• A Comparison of Elemental Abundance Ratios in Globular Clusters, Field Stars, and Dwarf Spheroidal Galaxies
• DAOSPEC: an automatic code for measuring equivalent widths in high-resolution stellar spectra
• First stars XII. Abundances in extremely metal-poor turnoff stars,and comparison with the giants
• Chemical abundance analysis of the Open Clusters Cr110, NGC2099 (M37), NGC2420, NGC7789 and M67 (NGC2682)
• Globular clusters in the outer Galactic halo: new HST/ACS imaging of 6 globular clusters and the Galactic globular cluster age-metallicity relation
• Atomic data for the Gaia-ESO Survey
• Building up the globular cluster system of the Milky Way. The contribution of the Sagittarius galaxy
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. IV. A New Sample of Open Clusters
• Sulphur and zinc abundances in Galactic halo stars revisited
• Sulphur and zinc abundances in Galactic stars and damped Lyman-alpha systems
• Ruprecht 106: the first single population Globular Cluster?
• The Effects of Age on Red Giant Metallicities Derived from the Near-Infrared Ca II Triplet
• Chemical abundance analysis of the Open Clusters Berkeley 32, NGC 752, Hyades and Praesepe
• Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
• C, S, Zn and Cu abundances in planet-harbouring stars
• On inelastic hydrogen atom collisions in stellar atmospheres
• Open clusters as key tracers of Galactic chemical evolution. III. Element abundances in Berkeley 20, Berkeley 29, Collinder 261, and Melotte 66
• The Chemo-Dynamical Groups of Galactic Globular Clusters
• The forbidden 1082 nm line of sulphur: the photospheric abundance of sulphur in the Sun and 3D effects
• Sulphur abundances in disk stars: a correlation with silicon
• The Infrared Ca II triplet as metallicity indicator
• Consistent metallicity scale for cool dwarfs and giants. A benchmark test using the Hyades
• Sulphur abundance in Galactic stars
• Sulphur abundance in very metal-poor stars
• The Gaia-ESO Survey: CNO abundances in the open clusters Trumpler 20, NGC 4815, and NGC 6705
• The Gaia-ESO Survey: Galactic evolution of sulphur and zinc
• The Similarity of Abundance Ratio Trends and Nucleosynthetic Patterns in the Milky Way Disk and Bulge
• First Stars XIV. Sulfur abundances in extremely metal-poor (EMP) stars
• A super lithium-rich red-clump star in the open cluster Trumpler 5
• The Gaia-ESO Survey: Reevaluation of the parameters of the open cluster Trumpler 20 using photometry and spectroscopy
• The Gaia-ESO Survey: Abundance ratios in the inner-disk open clusters Trumpler 20, NGC 4815, NGC 6705
• Sulphur abundances from the SI near-infrared triplet at 1045 nm
• The effects of differential reddening and stellar rotation on the appearance of multiple populations in star clusters: the case of Trumpler 20
• Ruprecht 106: A riddle, wrapped in a mystery, inside an enigma
• Sulphur in the Sculptor dwarf spheroidal galaxy - Including NLTE corrections
• Chemical abundance analysis of the old, rich open cluster Trumpler 20
• The old, metal-poor, anticentre open cluster Trumpler 5
• 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
• The Galactic evolution of sulphur as traced by globular clusters
• Milky Way Subsystems from Globular Clusters Kinematics Using Gaia DR2 and HST Data
• Sulphur abundances in disk stars as determined from the forbidden 10821 A [SI] line
• Trumpler 20 - an old and rich open cluster
• Study of the departures from LTE in the unevolved stars infra-red spectra
• Searching for Multiple Populations in Ruprecht 106
• 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
• Near-Infrared Photometric Study of the Old Open Cluster Trumpler 5

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