s-Process in Low Metallicity Stars. III. Individual analysis of CEMP-s and CEMP-s/r with AGB models

Abstract

We provide an individual analysis of 94 carbon enhanced metal-poor stars showing an s-process enrichment (CEMP-s) collected from the literature. The s-process enhancement observed in these stars is ascribed to mass transfer by stellar winds in a binary system from a more massive companion evolving faster toward the asymptotic giant branch (AGB) phase. The theoretical AGB nucleosynthesis models have been presented in Paper I. Several CEMP-s stars show an enhancement in both s and r-process elements (CEMP-s/r). In order to explain the peculiar abundances observed in CEMP-s/r stars, we assume that the molecular cloud from which CEMP-s formed was previously enriched in r-elements by Supernovae pollution. A general discussion and the method adopted in order to interpret the observations have been provided in Paper II. We present in this paper a detailed study of spectroscopic observations of individual stars. We consider all elements from carbon to bismuth, with particular attention to the three s-process peaks, ls (Y, Zr), hs (La, Nd, Sm) and Pb, and their ratios [hs/ls] and [Pb/hs]. The presence of an initial r-process contribution may be typically evaluated by the [La/Eu] ratio. We found possible agreements between theoretical predictions and spectroscopic data. In general, the observed [Na/Fe] (and [Mg/Fe]) provide information on the AGB initial mass, while [hs/ls] and [Pb/hs] are mainly indicators of the s-process efficiency. A range of 13C-pocket strengths is required to interpret the observations. However, major discrepancies between models and observations exist. We highlight star by star the agreements and the main problems encountered and, when possible, we suggest potential indications for further studies. These discrepancies provide starting points of debate for unsolved problems ...

40 pages, 54 figures, 3 tables (Appendix A as supplementary material), accepted Monthly Notices of the Royal Astronomical Society, 2012

References in corpus (32)

• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• Evolution, nucleosynthesis and yields of low mass AGB stars at different metallicities (II): the FRUITY database
• First Stars VIII -- Enrichment of the neutron-capture elements in the early Galaxy
• The s-Process in Low Metallicity Stars. II. Interpretation of High-Resolution Spectroscopic Observations with AGB models
• Short-lived Nuclei in the Early Solar System: Possible AGB Sources
• NLTE abundances of Mn in a sample of metal-poor stars
• Production of Light Element Primary Process nuclei in neutrino-driven winds
• 3D Hydrodynamical Simulations of Surface Convection in Red Giant Stars. Impact on spectral line formation and abundance analysis
• Nucleosynthesis in the Early Galaxy
• The Hamburg/ESO R-process Enhanced Star survey (HERES) III. HE 0338-3945 and the formation of the r+s stars
• NLTE determination of the sodium abundance in a homogeneous sample of extremely metal-poor stars
• Carbon-Enhanced Metal-Poor Stars. III. Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
• Non-LTE line formation for heavy elements in four very metal-poor stars
• Carbon Stars in the Hamburg/ESO Survey: Abundances
• First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor stars
• Evolution of the Barium abundance in the early Galaxy from a NLTE analysis of the Ba lines in a homogeneous sample of EMP stars
• Thermohaline mixing and gravitational settling in carbon-enhanced metal-poor stars
• CS 30322-023: an ultra metal-poor TP-AGB star?
• New analysis of the two carbon-rich stars CS 22948-27 and CS 29497-34 : binarity and neutron-capture elements
• CS22964-161: A Double-Lined Carbon- and s-Process-Enhanced Metal-Poor Binary Star
• Abundances of Sr, Y, and Zr in Metal-Poor Stars and Implications for Chemical Evolution in the Early Galaxy
• Magnetic Mixing in Red Giant and Asymptotic Giant Branch Stars
• A high-resolution spectral analysis of three carbon-enhanced metal-poor stars
• Analysis of 26 Barium Stars I. Abundances
• Carbon and Strontium Abundances of Metal-Poor Stars
• The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532
• Contrasting copper evolution in Omega Centauri and the Milky Way
• Abundance analysis of barium and mild barium stars
• Fluorine in carbon-enhanced metal-poor stars: a binary scenario
• Near-Infrared Spectroscopy of Carbon-Enhanced Metal-Poor Stars. I. A SOAR/OSIRIS Pilot Study
• The s-process in stellar population synthesis: a new approach to understanding AGB stars
• Carbon Abundances of Three Carbon-Enhanced Metal-Poor Stars from High-Resolution Gemini-S/bHROS Spectra of the 8727A [C I] Line

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• The odd-isotope fractions of Barium in CEMP-r/s star HE 0338-3945 and r-II star CS 31082-001
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