Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters

Abstract

We present an analysis of the s-process elements Zr, Ba, and La and the r-process element Eu in a sample of 50 stars in 19 open clusters. Stellar abundances of each element are based on measures of a minimum of two lines per species via both equivalent width and spectrum synthesis techniques. We investigate cluster mean neutron-capture abundance trends as a function of cluster age and location in the Milky Way disk and compare them to results found in other studies in the literature. We find a statistically significant trend of increasing cluster [Ba/Fe] as a function of decreasing cluster age, in agreement with recent findings for other open cluster samples, supporting the increased importance of low-mass asymptotic giant branch stars to the generation of s-process elements. However, the other s-process elements, [La/Fe] and [Zr/Fe], do not show similar dependences, in contrast to theoretical expectations and the limited observational data from other studies. Conversely, cluster [Eu/Fe] ratios show a slight increase with increasing cluster age, although with marginal statistical significance. Ratios of [s/r]-process abundances, [Ba/Eu] and [La/Eu], however, show more clearly the increasing efficiency of s-process relative to r-process enrichment in open cluster chemical evolution, with significant increases among younger clusters. Last, cluster neutron-capture element abundances appear to be independent of Galactocentric distance. We conclude that a homogeneous analysis of a larger sample of open clusters is needed to resolve the apparent discrepant conclusions between different studies regarding s-process element abundance trends with age to better inform models of galactic chemical evolution.

arXiv comment24 pages, 13 figures, 10 tables; published in The Astronomical Journal

References in corpus (30)

• The chemical composition of the Sun
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Cosmic-Ray Rejection by Laplacian Edge Detection
• The Chemical Compositions of Galactic Disk F and G Dwarfs
• alpha-, r-, and s-process element trends in the Galactic thin and thick disks
• Neutron-Capture Elements in the Early Galaxy: Insights from a Large Sample of Metal-Poor Giants
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• Nucleosynthesis and mixing on the Asymptotic Giant Branch. III. Predicted and observed s-process abundances
• The Galactic Thick Disk Stellar Abundances
• The Genesis of the Milky Way's Thick Disk via Stellar Migration
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. I. Open Clusters
• Chemical abundance analysis of the Open Clusters Cr110, NGC2099 (M37), NGC2420, NGC7789 and M67 (NGC2682)
• The age of the oldest Open Clusters
• The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. IV. A New Sample of Open Clusters
• Chemical abundance analysis of the Open Clusters Berkeley 32, NGC 752, Hyades and Praesepe
• A Chemical Abundance Study of 10 Open Clusters Based on WIYN-Hydra Spectroscopy
• Enhanced production of barium in low-mass stars: evidence from open clusters
• Accurate and homogeneous abundance patterns in solar-type stars of the solar neighbourhood: a chemo-chronological analysis
• Constraints on the Formation of the Galactic Bulge from Na, Al, and Heavy Element Abundances in Plaut's Field
• s-Processing in the Galactic Disk. I. Super-Solar Abundances of Y, Zr, La, Ce in Young Open Clusters
• News on the s process from young open clusters
• Comprehensive abundance analysis of red giants in the open clusters NGC 752, NGC 1817, NGC 2360 and NGC 2506
• The Unique Na:O Abundance Distribution in NGC 6791: The First Open(?) Cluster with Multiple Populations
• A New Look at the Old Star Cluster NGC 6791
• BVI photometry of the very old open cluster Berkeley 17
• Galactic Chemical Evolution of the s Process from AGB Stars
• Chemical compositions of thin-disk, high-metallicity red horizontal-branch field stars
• UBVI photometry of the intermediate age open cluster NGC 6939
• The anticenter old open cluster NGC 1883: radial velocity and metallicity

Cited by in corpus (47)

• First results from the IllustrisTNG simulations: A tale of two elements -- chemical evolution of magnesium and europium
• On the metallicity of open clusters II. Spectroscopy
• First light of the VLT planet finder SPHERE. I. Detection and characterization of the sub-stellar companion GJ 758 B
• 18 Sco: a solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging
• New insights on Ba over-abundance in open clusters. Evidence for the intermediate neutron-capture process at play?
• High-precision abundances of Sc, Mn, Cu, and Ba in solar twins. Trends of element ratios with stellar age
• The Gaia-ESO Survey: a new approach to chemically characterising young open clusters
• High-resolution abundance analysis of red giants in the globular cluster NGC 6522
• Abundance-age relations with red clump stars in open clusters
• GRACES observations of young [alpha/Fe]-rich stars
• Elemental Abundances of Solar Sibling Candidates
• The Gaia-ESO Survey: the origin and evolution of s-process elements
• s-Processing in AGB Stars Revisited. I. Does the Main Component Constrain the Neutron Source in the 13C-Pocket?
• A critical reassessment of the fundamental properties of GJ 504: Chemical composition and age
• The Gaia-ESO Survey: Age-chemical-clock relations spatially resolved in the Galactic disc
• O, Na, Ba and Eu abundance patterns in open clusters
• The Gaia-ESO Survey: A new approach to chemically characterising young open clusters II. Abundances of the neutron-capture elements Cu, Sr, Y, Zr, Ba, La, and Ce
• Spectroscopic Study of the Open Cluster NGC 6811
• Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447
• The Most Metal-poor Stars in the Magellanic Clouds are $r$-process Enhanced
• Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood
• Exploring the s-process history in the Galactic disk: Cerium abundances and gradients in Open Clusters from the OCCAM/APOGEE sample
• The Gaia-ESO Survey: the inner disk, intermediate-age open cluster Trumpler 23
• KIC 9821622: An interesting lithium-rich giant in the Kepler field
• Chemical diversity among A-B stars with low rotational velocities: non-LTE abundance analysis
• New Neutron-Capture Measurements in 23 Open Clusters. I. The R-Process
• Local associations and the barium puzzle
• The $Gaia$-ESO Survey: the inner disk intermediate-age open cluster NGC 6802
• WIYN Open Cluster Study: The Old Open Cluster, NGC 188, and a Re-evaluation of Lithium-Richness Among Red Giants
• NGC 7789: An Open Cluster Case Study
• First determination of s-process element abundances in pre-main sequence clusters: Y, Zr, La, and Ce in IC 2391, the Argus association and IC 2602
• The Most Metal-poor Stars in the Inner Bulge
• Photometric and spectroscopic study of the intermediate-age open cluster NGC 2355
• Chemical composition of evolved stars in the young open clusters NGC 4609 and NGC 5316
• A photometric and astrometric study of the open clusters NGC 1664 and NGC 6939
• Super lithium-rich K giant with low ${}^{12}\mathrm{C}$ to ${}^{13}\mathrm{C}$ ratio
• Chemical composition of giant stars in the open cluster IC 4756
• Searching for solar siblings among the HARPS data
• Modelling chemical clocks -- Theoretical evidences of the space and time evolution of [s/alpha] in the Galactic disc with Gaia-ESO survey
• Europium as a lodestar: diagnosis of radiogenic heat production in terrestrial exoplanets
• Prospecting for chemical tags among open clusters
• Properties of the open cluster Tombaugh 1 from high resolution spectroscopy and uvbyCaH$\beta$ photometry
• Heavy elements in old very metal-rich stars
• A wide angle view of the Sagittarius dwarf spheroidal galaxy -- II. A CEMP-r/s star in the Sagittarius dwarf Spheroidal Galaxy
• Radial velocities and metallicities of red giant stars in the old open cluster NGC 7762
• Peculiarities of α-element abundances in Galactic open clusters
• Peculiarities of the abundances of neutron-capture elements in Galactic open clusters