Chemical abundances along the 1G sequence of the chromosome maps: The Globular Cluster NGC 3201

Abstract

The Hubble Space Telescope (HST) UV Legacy Survey of Galactic Globular Clusters (GCs) has investigated multiple stellar populations by means of the "chromosome map" (ChM) diagnostic tool that maximises the separation between stars with different chemical composition. One of the most challenging features revealed by ChMs analysis is the apparent inhomogeneity among stars belonging to the first population, a phenomenon largely attributed to He variations. However, this explanation is not supported by the uniformity in p-capture elements of these stars. The HST survey has revealed that the GC NGC 3201 shows an exceptionally wide coverage in the Delta(F275W,F814W) parameter of the ChM. We present a chemical abundance analysis of 24 elements in 18 giants belonging to the first population of this GC, and having a wide range in Delta(F275W,F814W). As far as the p-capture elements are concerned, the chemical abundances are typical of 1G stars, as expected from the location of our targets in the ChM. Based on radial velocities and chemical abundances arguments, we find that the three stars with the lowest Delta(F275W,F814W) values are binary candidates. This suggests that, at least those stars could be explained with binarity. These results are consistent with evidence inferred from multi-band photometry that evolved blue stragglers populate the bluest part of the 1G sequence in the ChM. The remaining 15 spectroscopic targets show a small range in the overall metallicity by ~0.10 dex, with stars at higher Delta(F275W,F814W) values having higher absolute abundances. We suggest that a small variation in metals and binarity govern the color spread of the 1G in the ChM, and that evolved blue stragglers contribute to the bluest tail of the 1G sequence.

24 pages, 12 figures, 8 tables. Accepted for publication in ApJ

References in corpus (14)

• The Dawes Review 2: Nucleosynthesis and stellar yields of low and intermediate-mass single stars
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
• An abundance analysis of bright giants in the globular cluster NGC 1851
• Evolution and nucleosynthesis of asymptotic giant branch stellar models of low metallicity
• Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites
• A Binary Origin for Blue Stragglers in Globular Clusters
• Nitrogen abundances in giant stars of the globular cluster NGC 6752
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. II. The seven stellar populations of NGC7089 (M2)
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. XIX. A Chemical Tagging of the Multiple Stellar Populations Over the Chromosome Maps
• The chemical compositions of solar twins in the open cluster M67
• Is helium the key parameter in the extended color spread of the first generation stars in M3?
• Constant light element abundances suggest that the extended P1 in NGC 2808 is not a consequence of CNO-cycle nucleosynthesis

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