New Neutron-Capture Measurements in 23 Open Clusters. I. The R-Process

Abstract

Neutron-capture elements, those with Z > 35, are the least well-understood in terms of nucleosynthesis and formation environments. The rapid neutron-capture, or r-process, elements are formed in the environments and/or remnants of massive stars, while the slow neutron-capture, or s-process, elements are primarily formed in low-mass AGB stars. These elements can provide much information about Galactic star formation and enrichment, but observational data is limited. We have assembled a sample of 68 stars in 23 open clusters that we use to probe abundance trends for six neutron-capture elements (Eu, Gd, Dy, Mo, Pr, and Nd) with cluster age and location in the disk of the Galaxy. In order to keep our analysis as homogenous as possible, we use an automated synthesis fitting program, which also enables us to measure multiple (3-10) lines for each element. We find that the pure r-process elements (Eu, Gd, and Dy) have positive trends with increasing cluster age, while the mixed r- and s- process elements (Mo, Pr, and Nd) have insignificant trends consistent with zero. Pr, Nd, Eu, Gd, and Dy have similar, slight (though mostly statistically significant) gradients of ~0.04 dex/kpc. The mixed elements also appear to have nonlinear relationships with Galactocentric radius.

arXiv comment28 pages, 12 figures, 11 tables including two MRT. Accepted for publication in the Astrophysical Journal

References in corpus (48)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Elemental Abundance Survey of The Galactic Thick Disk
• The Chemical Compositions of Galactic Disk F and G Dwarfs
• Radioactive 26Al and massive stars in the Galaxy
• Galactic Evolution of Sr, Y, Zr: A Multiplicity of Nucleosynthetic Processes
• Some Revised Observational Constraints on the Formation and Evolution of the Galactic Disk
• Spectroscopic Studies of Extremly Metal-Poor Stars with Subaru/HDS:II.The r-process Elements, Including Thorium
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• The Distribution of the Elements in the Galactic Disk III. A Reconsideration of Cepheids from l = 30 to 250 Degrees
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. I. Open Clusters
• Fundamental Parameters and Chemical Composition of Arcturus
• Chemical abundance analysis of the Open Clusters Cr110, NGC2099 (M37), NGC2420, NGC7789 and M67 (NGC2682)
• New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars
• On the galactic disc age-metallicity relation
• The age of the oldest Open Clusters
• Galactic evolution of rapid neutron capture process abundances: the inhomogeneous approach
• Using Cepheids to determine the galactic abundance gradient I. The solar neighbourhood
• Elemental Abundance Ratios in Stars of the Outer Galactic Disk. IV. A New Sample of Open Clusters
• Using Cepheids to determine the galactic abundance gradient II. Towards the galactic center
• Radial Mixing in Galactic Disks: The Effects of Disk Structure and Satellite Bombardment
• Chemical Homogeneity in Collinder 261 and Implications for Chemical Tagging
• Using Cepheids to determine the galactic abundance gradient. III.First results for the outer disc
• 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
• The Bologna Open Cluster Chemical Evolution (BOCCE) Project: midterm results from the photometric sample
• The orbits of open clusters in the Galaxy
• Enhanced production of barium in low-mass stars: evidence from open clusters
• The chemical abundance of the very metal rich old Open Clusters NGC 6253 and NGC 6791
• The chemical evolution of Barium and Europium in the Milky Way
• CCD BV survey of 42 open clusters
• New insights on Ba over-abundance in open clusters. Evidence for the intermediate neutron-capture process at play?
• 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
• High-resolution spectroscopy of the old open cluster Collinder 261:abundances of Iron and other elements
• Cosmic Neutron Star Merger Rate and Gravitational Waves constrained by the R Process Nucleosynthesis
• Comprehensive abundance analysis of red giants in the open clusters NGC 2527, 2682, 2482, 2539, 2335, 2251 and 2266
• Zirconium, Barium, Lanthanum and Europium Abundances in Open Clusters
• Carbon and oxygen isotopic ratios in Arcturus and Aldebaran: Constraining the parameters for non convective mixing on the RGB
• A kinematic study of Open Clusters: implications for their origin
• Open clusters towards the Galactic center: chemistry and dynamics. A VLT spectroscopic study of NGC6192, NGC6404, NGC6583
• Comprehensive abundance analysis of red giants in the open clusters NGC 1342, 1662, 1912, 2354 and 2447
• Galactic Chemical Evolution of the s Process from AGB Stars
• The solar photospheric abundance of europium. Results from CO5BOLD 3-D hydrodynamical model atmospheres
• C, N and O abundances in red clump stars of the Milky Way
• NGC 7789: An Open Cluster Case Study
• Three new bricks in the wall: Berkeley 23, Berkeley 31, and King 8
• UBVI photometry of the intermediate age open cluster NGC 6939
• Elemental abundances of intermediate age open cluster NGC 3680

Cited by in corpus (18)

• The APOGEE Data Release 16 Spectral Line List
• The Open Cluster Chemical Abundances and Mapping Survey: II. Precision Cluster Abundances for APOGEE using SDSS DR14
• The Gaia-ESO Survey: the origin and evolution of s-process elements
• Abundances of neutron-capture elements in thin- and thick-disc stars in the solar neighbourhood
• The Gaia-ESO Survey: Calibrating the lithium-age relation with open clusters and associations. I. Cluster age range and initial membership selections
• The AMBRE Project: r-process elements in the Milky Way thin and thick discs
• The Gaia-ESO Survey: the inner disk, intermediate-age open cluster Trumpler 23
• A study of the NGC 1193 and NGC 1798 open clusters using CCD UBV photometric and Gaia EDR3 data
• Determination of dynamical ages of open clusters through the A${}^{+}$ parameter -- I
• Variability in the Massive Open Cluster NGC 1817 from K2: A Rich Population of Asteroseismic Red Clump, Eclipsing Binary, and Main Sequence Pulsating Stars
• Chemical composition of evolved stars in the young open clusters NGC 4609 and NGC 5316
• Stellar population astrophysics (SPA) with the TNG -- The Arcturus Lab
• Chemical composition of giant stars in the open cluster IC 4756
• Galactic r-process abundance feature shaped by radial migration
• Exploring fluorine chemical evolution in the Galactic disk: the open cluster perspective
• Triangulum-Andromeda overdensity: a region with a complex stellar population
• Abundances of disk and bulge giants from high-resolution optical spectra V. Molybdenum -- the p-process element
• TYCHO -- Realistically Simulating Exoplanets within Stellar Clusters I: Improving the Monte Carlo Approach