The Hamburg/ESO R-process Enhanced Star survey (HERES) X. HE 2252-4225, one more r-process enhanced and actinide-boost halo star

Abstract

We report on a detailed abundance analysis of the r-process enhanced giant star, HE 2252-4225 ([Fe/H] = -2.63, [r/Fe] = 0.80). Determination of stellar parameters and element abundances was based on analysis of high-quality VLT/UVES spectra. The surface gravity was calculated from the NLTE ionisation balance between Fe I and Fe II. Accurate abundances were determined for a total of 38 elements, including 22 neutron-capture elements beyond Sr and up to Th. This object is deficient in carbon, as expected for a giant star with Teff < 4800 K. The stellar Na-Zn abundances are well fitted by the yields of a single supernova of 14.4 Msun. For the neutron-capture elements in the Sr-Ru, Ba-Yb, and Os-Ir regions, the abundance pattern of HE 2252-4225 is in excellent agreement with the average abundance pattern of the strongly r-process enhanced stars CS 22892-052, CS 31082-001, HE 1219-0312, and HE 1523-091. This suggests a common origin of the first, second, and third r-process peak elements in HE 2252-4225 in the classical r-process. We tested the solar r-process pattern based on the most recent s-process calculations of Bisterzo et al. (2014) and found that elements in the range from Ba to Ir match it very well. No firm conclusion can be drawn about the relationship between the fisrt neutron-capture peak elements, Sr to Ru, in HE 2252-4225 and the solar r-process, due to the uncertainty in the solar r-process. The investigated star has an anomalously high Th/Eu abundance ratio, so that radioactive age dating results in a stellar age of tau = 1.5+-1.5 Gyr that is not expected for a very metal-poor halo star.

20 pages, 6 tables, 9 figures, accepted for publication in A&A

References in corpus (22)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• Galactic Chemical Evolution and solar s-process abundances: dependence on the 13C-pocket structure
• Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium
• Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
• NLTE abundances of Mn in a sample of metal-poor stars
• A non-LTE study of neutral and singly-ionized calcium in late-type stars
• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• Both accurate and precise gf-values for FeII lines
• The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
• Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars
• Detection of Elements at All Three r-process Peaks in the Metal-Poor Star HD 160617
• Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data
• NLTE determination of the aluminium abundance in a homogeneous sample of extremely metal-poor stars
• Non-LTE line formation for heavy elements in four very metal-poor stars
• Improved Laboratory Transition Probabilities for Er II and Applications to the Erbium Abundances of the Sun and Five r-Process Rich, Metal-Poor Stars
• High-resolution abundance analysis of very metal-poor r-I stars
• Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I
• Fundamental properties of the Population II fiducial stars HD 122563 and Gmb 1830 from CHARA interferometric observations
• Statistical equilibrium of silicon in the solar atmosphere
• Non-LTE Sodium Abundance in Galactic Thick- and Thin-Disk Red Giants
• The Hamburg/ESO R-process Enhanced Star survey (HERES) IX. Constraining pure r-process Ba/Eu abundance ratio from observations of r-II stars

Cited by in corpus (32)

• Neutrino Fast Flavor Conversions in Neutron-star Post-Merger Accretion Disks
• Kilonovae across the nuclear physics landscape: The impact of nuclear physics uncertainties on r-process-powered emission
• Magnetorotational supernovae: A nucleosynthetic analysis of sophisticated 3D models
• Coalescence of black hole--neutron star binaries
• The R-Process Alliance: Chemo-Dynamically Tagged Groups of Halo $r$-Process-Enhanced Stars Reveal a Shared Chemical-Evolution History
• Nucleosynthesis and observation of the heaviest elements
• Probing the production of actinides under different r-process conditions
• The R-Process Alliance: Abundance Universality among Some Elements at and between the First and Second R-Process Peaks
• Constraints on stellar rotation from the evolution of Sr and Ba in the Galactic halo
• 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
• Igniting weak interactions in neutron star postmerger accretion disks
• R-process-rich stellar streams in the Milky Way
• Correlations of r-Process Elements in Very Metal-Poor Stars as Clues to their Nucleosynthesis Sites
• Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
• The Origin of the Heaviest Metals in Most Ultra-Faint Dwarf Galaxies
• Enrichment of Strontium in Dwarf Galaxies
• Reconstructing Masses of Merging Neutron Stars from Stellar $R$-Process Abundance Signatures
• Decoding the compositions of four bright $r$-process-enhanced stars
• $S^5$: The destruction of a bright dwarf galaxy as revealed by the chemistry of the Indus stellar stream
• Uranium Abundances and Ages of $R$-process Enhanced Stars with Novel U II Lines
• Finding $r$-II sibling stars in the Milky Way with the Greedy Optimistic Clustering algorithm
• Searching for r-process-enhanced stars in the LAMOST Survey I: The Method
• r-Process enrichment in the Galactic halo characterized by nucleosynthesis variation in the ejecta of coalescing neutron star binaries
• Chemical Evolution of R-process Elements in Stars (CERES). III. Chemical abundances of neutron capture elements from Ba to Eu
• Europium enrichment and hierarchical formation of the Galactic halo
• A Nuclear Equation of State Inferred from Stellar r-process Abundances
• Enrichment of the Galactic disc with neutron-capture elements: Gd, Dy, and Th
• Characterizing $r$-Process Sites through Actinide Production
• Detection of the actinide Th in an r-process-enhanced star with accretion origin
• An Actinide-boost Star Discovered in the Gaia-Sausage-Enceladus
• Recent Advances in Understanding R-Process Nucleosynthesis in Metal-Poor Stars and Stellar Systems
• On the Chemical Composition of the Evolved Very Bright Metal-Poor Star HD 1936