Th Ages for Metal-Poor Stars

Abstract

With a sample of 22 metal-poor stars, we demonstrate that the heavy element abundance pattern (Z > 55) is the same as the r-process contributions to the solar nebula. This bolsters the results of previous studies that there is a universal r-process production pattern. We use the abundance of thorium in five metal-poor stars, along with an estimate of the initial Th abundance based on the abundances of stable r-process elements, to measure their ages. We have four field red giants with errors of 4.2 Gyr in their ages and one M92 giant with an error of 5.6 Gyr, based on considering the sources of observational error only. We obtain an average age of 11.4 Gyr, which depends critically on the assumption of an initial production ratio of Th/Eu of 0.496. If the Universe is 15 Gyr old, then the initial Th/Eu value should be 0.590, in agreement with some theoretical models of the r-process.

26 pages, to be published in ApJ

References in corpus (9)

• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Measurements of Omega and Lambda from 42 High-Redshift Supernovae
• Neutron capture in low mass Asymptotic Giant Branch stars: cross sections and abundance signatures
• Neutron-Capture Elements in the Early Galaxy: Insights from a Large Sample of Metal-Poor Giants
• Distances, ages, and epoch of formation of globular clusters
• The r-Process Enriched Low Metallicity Giant HD 115444
• Galactic chemical evolution of heavy elements: from Barium to Europium
• R-Process Abundances and Chronometers in Metal-Poor Stars
• Lead: Asymptotic Giant Branch production and Galactic Chemical Evolution

Cited by in corpus (62)

• The New Galaxy: Signatures of its Formation
• Stellar Chemical Signatures And Hierarchical Galaxy Formation
• The Extremely Metal-Poor, Neutron-Capture-Rich Star CS 22892-052: A Comprehensive Abundance Analysis
• The extreme r-element rich, iron-poor halo giant CS31082-001: Implications for the r-process site(s) and radioactive cosmochronology
• Spectroscopic Studies of Extremly Metal-Poor Stars with Subaru/HDS:II.The r-process Elements, Including Thorium
• Detailed Abundances for 28 Metal-poor Stars: Stellar Relics in the Milky Way
• The Chemical Composition and Age of the Metal-Poor Halo Star BD +17^\circ 3248
• A Comparison of Elemental Abundance Ratios in Globular Clusters, Field Stars, and Dwarf Spheroidal Galaxies
• Abundances of 30 elements in 23 metal-poor stars
• The s-Process in Low Metallicity Stars. II. Interpretation of High-Resolution Spectroscopic Observations with AGB models
• Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
• Neutron-capture elements in the very metal-poor star HD122563
• O/Fe in metal-poor main sequence and subgiant stars
• 'Sculptor'-ing the Galaxy? The Chemical Compositions of Red Giants in the Sculptor Dwarf Spheroidal Galaxy
• From Nuclei to the Cosmos: Tracing Heavy-Element Production with the Oldest Stars
• Explorations of the r-Processes: Comparisons between Calculations and Observations of Low-Metallicity Stars
• Tuning the Clock: Uranium and Thorium Chronometers Applied to CS 31082-001
• Neutron-capture elements in the very metal-poor star HD88609: another st ar with excesses of light neutron-capture elements
• The Hamburg/ESO R-process Enhanced Star survey (HERES). I. Project description, and discovery of two stars with strong enhancements of neutron-capture elements
• Probing the Neutron-Capture Nucleosynthesis History of Galactic Matter
• VLT/UVES Spectroscopy of Individual Stars in Three Globular Clusters in the Fornax Dwarf Spheroidal Galaxy
• Stellar Archaeology -- Exploring the Universe with Metal-Poor Stars
• The Origin of the Heavy Elements: Recent Progress in the Understanding of the r-Process
• Abundance Analysis of HE2148-1247, A Star With Extremely Enhanced Neutron Capture Elements
• The r-process in the neutrino winds of core-collapse supernovae and U-Th cosmochronology
• The End of Nucleosynthesis: Production of Lead and Thorium in the Early Galaxy
• r-Process Calculations and Galactic Chemical Evolution
• The r-process in the early Galaxy
• Stellar Sources for Heavy r-Process Nuclei
• The s-process in metal-poor stars: Abundances for 22 neutron-capture elements in CS 31062-050
• Actinides: How well do we know their stellar production?
• The Hamburg/ESO R-process Enhanced Star survey (HERES) X. HE 2252-4225, one more r-process enhanced and actinide-boost halo star
• A Model for Abundances in Metal-Poor Stars
• Detailed Abundances of Two Very Metal-Poor Stars in Dwarf Galaxies
• The Isotopic Mixture of Barium in the Metal-poor Subgiant HD 140283
• From actinides to zinc: Using the full abundance pattern of the brightest star in Reticulum II to distinguish between different r-process sites
• Characterizing the Heavy Elements in Globular Cluster M22 and an Empirical s-process Abundance Distribution Derived from the Two Stellar Groups
• Spectroscopic Studies of Extremely Metal-Poor Stars with Subaru/HDS:I. Observational Data
• r-Process Abundance Universality and Actinide Cosmochronology
• Enrichment of Very Metal-Poor Stars with Both r-Process and s-Process Elements from 8-10 M_\odot Stars
• Chemical Abundances for Evolved Stars in M5: Lithium through Thorium
• Detailed Abundances of 15 Stars in the Metal-Poor Globular Cluster NGC 4833
• The 139La(n,gamma) cross section: key for the onset of the s process
• Thorium in solar twins: implications for habitability in rocky planets
• The R-Process Alliance: J1521-3538, a very metal-poor, extremely r-process-enhanced star with [Eu/Fe]=+2.2, and the class of r-III stars
• Thorium-rich halo star HD221170: further evidence against the universality of the r-process
• Atomic and Molecular Data for Stellar Physics: Former Successes and Future Challenges
• The Origin of the Heaviest Metals in Most Ultra-Faint Dwarf Galaxies
• The Hamburg/ESO R-process Enhanced Star survey (HERES)VII. Thorium abundances in metal-poor stars
• Decoding the compositions of four bright $r$-process-enhanced stars
• Reconstructing Masses of Merging Neutron Stars from Stellar $R$-Process Abundance Signatures
• Gaia-Sausage-Enceladus star formation history as revealed by detailed elemental abundances
• 138La-138Ce-136Ce nuclear cosmochronometer of supernova neutrino process
• Supernova Neutrino-Effects on R-Process Nucleosynthesis in Black Hole Formation
• The age of the Galactic thin disk from Th/Eu nucleocosmochronology II. Chronological analysis
• Accuracy of spectroscopy-based radioactive dating of stars
• Nuclear physics and astrophysics of the r-process
• Observations of Neutron-Capture Elements in the Early Galaxy
• Galactic Cosmochronometry from Radioactive Elements in the Spectra of Very Old Metal-Poor Stars
• r-Process Enhanced Halo Stars
• Metal-Poor Globular Clusters of the Milky Way and Environs
• Observations of r- and s-process elements in Population II stars