Peculiarities of the abundances of neutron-capture elements in Galactic open clusters

Abstract

The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14~elements produced in various nuclear-synthesis processes for 90~open clusters. The catalog also contains the positions, ages, velocities, and elements of the Galactic orbits of the clusters. The relative abundances of both $r$-elements (Eu) and $s$-elements (Y, Ba, La, and Ce) in clusters with high, elongated orbits and in field stars of the Galactic thin disk display different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits, supporting the view that these objects have different natures. In young clusters, not only barium, but also the three other studied $s$-elements display significantly higher relative abundances than field stars of the same metallicity. The relative abundances of Eu are lower in high-metallicity clusters ($[Fe/H]>-0.1$) with high, elongated orbits than in field giants, on average, while the [Eu/Fe] ratios in lower-metallicity clusters are the same as those in field stars, on average, although with a large scatter. The metallicity dependence of the [O, Mg/Eu] ratios in clusters with high, elongated orbits and in field stars are substantially different. These and other described properties of the Eu abundances, together with the properties of the abundances of primary $\alpha$-elements, can be understood in a natural way if clusters with high, elongated orbits with different metallicities formed as a result of interactions of two types of high-velocity clouds with the interstellar medium of the Galactic disk: low-metallicity high-velocity clouds that formed from "primordial" gas, and high-metallicity clouds with intermediate velocities that formed in "Galactic fountains".

arXiv comment14 pages, 3 figures

References in corpus (18)

• Abundances for metal-poor stars with accurate parallaxes I. Basic data
• The s-Process in Low Metallicity Stars. II. Interpretation of High-Resolution Spectroscopic Observations with AGB models
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. IV. A New Sample of Open Clusters
• The orbits of open clusters in the Galaxy
• Enhanced production of barium in low-mass stars: evidence from open clusters
• Abundances of neutron-capture elements in stars of the galactic disk substructures
• s-Processing in the Galactic Disk. I. Super-Solar Abundances of Y, Zr, La, Ce in Young Open Clusters
• New insights on Ba over-abundance in open clusters. Evidence for the intermediate neutron-capture process at play?
• Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters
• A kinematic study of Open Clusters: implications for their origin
• The chemical composition of nearby young associations: s-process element abundances in AB Doradus, Carina-Near, and Ursa Major
• Barium Abundances in Cepheids
• Galactic Chemical Evolution of the s Process from AGB Stars
• Heterogeneity of the Population of Open Star Clusters in the Galaxy
• Two Populations of Open Star Clusters in the Galaxy
• Formation of Galactic Systems in Light of the Magnesium Abundance in Field Stars: The Thin Disk
• The Age-Metallicity Relation in the Thin Disk of the Galaxy
• Peculiarities of α-element abundances in Galactic open clusters

Cited by in corpus (4)

• The Gaia-ESO Survey: Age-chemical-clock relations spatially resolved in the Galactic disc
• Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood
• Chemical composition of evolved stars in the young open clusters NGC 4609 and NGC 5316
• On the Metallicity Gradient in the Galactic Disk