Neutron-capture elements in a sample of field metal-poor N-rich dwarfs

Abstract

The aim of this work is to measure the abundances of n-capture elements in a sample of six metal-poor N-rich dwarfs that were formed in globular clusters, and subsequently became unbound from the cluster. These N-rich stars, HD 25329, HD 74000, HD 160617, G 24-3, G 53-41, and G 90-3, were previously studied in Paper I. The abundances of the n-capture elements in these stars were compared to the abundances in normal metal-poor dwarfs and in globular cluster stars in the same metallicity range in order to find evidence of an enrichment of the material from which these N-rich stars were formed, by the ejecta of massive asymptotic giant branch stars (AGB) inside the cluster.The abundances of 15 elements, from Sr to Yb, were derived line by line by comparing the observed profiles to synthetic spectra in a sample of six metal-poor N-rich dwarfs and nine classical metal-poor dwarfs. We show that, generally speaking, the behaviours of the intermediate metal-poor stars here studied and the extremely metal-poor stars are very different. In particular, the scatter of the [X/Fe] ratios is much smaller since many more stars contribute to the enrichment.Among our six metal-poor N-rich stars, three stars (G24-3 and HD 74000 and maybe also HD 160617) present an enrichment in elements formed by the s-process, typical of a contribution of AGB stars, unexpected at the metallicity of these stars. This suggests that the intracluster medium from which these stars were formed was enriched by a first generation of massive AGB stars. Another N-rich star, G53-41, is also rich in s-process elements, but since it is more metal-rich this could be due to the normal galactic enrichment by low-mass AGB stars before the formation of the cluster. In contrast, two stars (G90-3 and HD 25329) have an abundance pattern compatible with a pure r-process such as that seen in metal-poor stars with [Fe/H]<--1.5.

References in corpus (51)

• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 3: Summary of the content and survey properties
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Neutron capture in low mass Asymptotic Giant Branch stars: cross sections and abundance signatures
• Solar Chemical Abundances Determined with a CO5BOLD 3D Model Atmosphere
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• Origin of the Heaviest Elements: the Rapid Neutron-Capture Process
• The Geneva-Copenhagen Survey of the Solar neighbourhood III. Improved distances, ages, and kinematics
• The Extremely Metal-Poor, Neutron-Capture-Rich Star CS 22892-052: A Comprehensive Abundance Analysis
• Abundances of the elements in the solar system
• The extreme r-element rich, iron-poor halo giant CS31082-001: Implications for the r-process site(s) and radioactive cosmochronology
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• The Abundances of Neutron Capture Species in the Very Metal-Poor Globular Cluster M15: An Uniform Analysis of RGB and RHB Stars
• $s$-process production in rotating massive stars at solar and low metallicities
• Neutron-capture elements in the very metal-poor star HD122563
• Charged-Particle and Neutron-Capture Processes in the High-Entropy Wind of Core-Collapse Supernovae
• Non-standard s process in low metallicity massive rotating stars
• The Ubiquity of the Rapid Neutron-Capture Process
• Chromospheric activity as age indicator
• Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites
• Neutron-capture elements in the very metal-poor star HD88609: another st ar with excesses of light neutron-capture elements
• Iron and neutron-capture element abundance variations in the globular cluster M2 (NGC 7089)
• Astronuclear Physics: a Tale of the Atomic Nuclei in the Skies
• The s-process in the Galactic halo: the fifth signature of spinstars in the early Universe?
• First stars XVI. STIS/HST abundances of heavy-elements in the uranium-rich star CS 31082-001
• A Spectroscopic Analysis of the Galactic Globular Cluster NGC 6273 (M19)
• High-resolution abundance analysis of very metal-poor r-I stars
• Cold r-Process in Neutrino-Driven Winds
• Ba & Eu Abundances in M15 giant stars
• Ultra-Lithium-Deficient Halo Stars and Blue Stragglers: A Common Origin?
• Heavy Element Dispersion in the Metal-Poor Globular Cluster M92
• Characterizing the Heavy Elements in Globular Cluster M22 and an Empirical s-process Abundance Distribution Derived from the Two Stellar Groups
• MARCS model atmospheres
• Detailed Chemical Abundances in NGC 5824: Another Metal-Poor Globular Cluster with Internal Heavy Element Abundance Variations
• Chemical abundances in bright giants of the globular cluster M62 (NGC 6266)
• Abundance patterns of the light neutron-capture elements in very and extremely metal-poor stars
• Heavy elements abundances in turn-off stars and early subgiants in NGC 6752
• The Extreme Overabundance of Molybdenum in Two Metal-Poor Stars
• Co-production of light p-, s- and r-process isotopes in the high-entropy wind of type II supernovae
• Detailed Abundances of 15 Stars in the Metal-Poor Globular Cluster NGC 4833
• High-resolution abundance analysis of HD 140283
• Molybdenum, Ruthenium, and the Heavy r-process Elements in Moderately Metal-Poor Main-Sequence Turnoff Stars
• The chemical DNA of the Magellanic Clouds -- I. The chemical composition of 206 Small Magellanic Cloud red giant stars
• Correlations of r-Process Elements in Very Metal-Poor Stars as Clues to their Nucleosynthesis Sites
• Neutron-capture elements in dwarf galaxies II: Challenges for the s- and i-processes at low metallicity
• Origin of the heavy elements in HD 140283. Measurement of europium abundance
• Abundances of the light elements from UV (HST) and red (ESO) spectra in the very old star HD 84937
• Reanalysis of neutron-capture elements in the benchmark r-rich star CS 31082-001
• Detailed analysis of a sample of field metal-poor N-rich dwarfs