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A complex interplay between mixing and nucleosynthesis is at work in asymptotic giant branch (AGB) stars. In addition to the slow neutron capture process (s-process), the intermediate neutron capture process (i-process) can develop during…

Solar and Stellar Astrophysics · Physics 2025-04-14 Arthur Choplin , Stephane Goriely , Lionel Siess , Sébastien Martinet

We report the abundances of neutron-capture elements in eight carbon-rich, metal-poor (-2.7=<[Fe/H]=<-1.9) stars observed with the Subaru Telescope High Dispersion Spectrograph. The derived abundance patterns indicate that the…

Astrophysics · Physics 2008-11-26 W. Aoki , S. G. Ryan , J. E. Norris , T. C. Beers , H. Ando

We examine the Pb and Th abundances in 27 metal-poor stars (-3.1 < [Fe/H] < -1.4) whose very heavy metal (Z > 56) enrichment was produced only by the rapid (r-) nucleosynthesis process. New abundances are derived from HST/STIS, Keck/HIRES,…

Solar and Stellar Astrophysics · Physics 2011-02-11 Ian U. Roederer , Karl-Ludwig Kratz , Anna Frebel , Norbert Christlieb , Bernd Pfeiffer , John J. Cowan , Christopher Sneden

Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Generally higher temperatures and nuclear level densities lead to stronger contributions of transitions on…

Nuclear Experiment · Physics 2022-10-26 T. Rauscher

In order to study the processes creating intermediate and heavy nuclei in massive stars it is necessary to provide neutron capture cross sections and reaction rates close to stability and for moderately unstable neutron-rich nuclei.…

Astrophysics · Physics 2007-05-23 T. Rauscher , A. Heger , S. E. Woosley , R. D. Hoffman

The propagation of uncertainties in reaction cross sections and rates of neutron-, proton-, and alpha-induced reactions into the final isotopic abundances obtained in nucleosynthesis models is an important issue in studies of…

High Energy Astrophysical Phenomena · Physics 2025-01-07 T. Rauscher , N. Nishimura , G. Cescutti , R. Hirschi , A. St. J. Murphy , C. Travaglio

The synthesis of nuclei in diverse cosmic scenarios is reviewed, with a summary of the basic concepts involved before a discussion of the current status in each case is made. We review the physics of the early universe, the proton to…

Nuclear Theory · Physics 2016-06-22 Carlos A. Bertulani , Toshitaka Kajino

The origin of carbon-enhanced metal-poor (CEMP) stars plays a key role in characterising the formation and evolution of the first stars and the Galaxy since the extremely-poor (EMP) stars with [Fe/H] \leq -2.5 share the common features of…

Solar and Stellar Astrophysics · Physics 2017-03-29 Takuma Suda , Shimako Yamada , Masayuki Y. Fujimoto

Carbon enhanced metal poor (CEMP) stars with low abundances of neutron capture elements (CEMP-no stars) are ubiquitous among metal poor stars in the Milky Way. Recent observations have uncovered their two subgroups that differ in the carbon…

Astrophysics of Galaxies · Physics 2018-11-14 Mahavir Sharma , Tom Theuns , Carlos Frenk

The radiative neutron capture cross section of 207Pb has been measured at the CERN neutron time of flight installation n_TOF using the pulse height weighting technique in the resolved energy region. The measurement has been performed with…

Nuclear Experiment · Physics 2008-11-26 C. Domingo-Pardo

Recently an increasing number of studies were devoted to measure the abundances of neutron-capture elements heavier than iron in stars belonging to Galactic Open Clusters (OCs). OCs span a sizeable range in metallicity -0.6<[Fe/H]<+0.4),…

Solar and Stellar Astrophysics · Physics 2015-06-23 T. Mishenina , M. Pignatari , G. Carraro , V. Kovtyukh , L. Monaco , S. Korotin , E. Shereta , I. Yegorova , F. Herwig

Heavy elements, those produced by neutron-capture reactions, have traditionally shown no star-to-star dispersion in all but a handful of metal-poor globular clusters (GCs). Recent detections of low [Pb/Eu] ratios or upper limits in several…

Astrophysics of Galaxies · Physics 2011-05-11 Ian U. Roederer

We present model predictions for the Zr isotopic ratios produced by slow neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25 to 4 Msun and metallicities Z=0.01 to 0.03, and compare them to data from single…

Ground- and space-based observations of stellar heavy element abundances are providing a clearer picture of the chemical evolution of the Galaxy. A large number of (r)apid and (s)low neutron capture process elements, including the first…

Astrophysics · Physics 2007-05-23 John J Cowan , Christopher Sneden , James W Truran , Debra L Burris

The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14~elements produced in various nuclear-synthesis processes for 90~open…

Astrophysics of Galaxies · Physics 2016-02-22 V. A. Marsakov , M. L. Gozha , V. V. Koval' , L. V. Shpigel'

The detailed composition of most metal-poor halo stars has been found to be very uniform. However, a fraction of 20-70% (increasing with decreasing metallicity) exhibit dramatic enhancements in their abundances of carbon - the so-called…

Solar and Stellar Astrophysics · Physics 2016-02-24 T. T. Hansen , J. Andersen , B. Nordström , T. C. Beers , V. M. Placco , J. Yoon , L. A. Buchhave

The $\nu p$ process appears in proton-rich, hot matter which is expanding in a neutrino wind and may be realised in explosive environments such as core-collapse supernovae or in outflows from accretion disks. The impact of uncertainties in…

High Energy Astrophysical Phenomena · Physics 2020-03-30 T. Rauscher , N. Nishimura , G. Cescutti , R. Hirschi , A. St. J. Murphy , C. Fröhlich

The abundances of heavy elements in EMP stars are not well explained by the simple view of an initial basic "rapid" process. In a careful and homogeneous analysis of the "First stars" sample (eighty per cent of the stars have a metallicity…

Solar and Stellar Astrophysics · Physics 2015-06-17 Monique Spite , François Spite

Exploring nucleon drip lines and astrophysical rapid neutron capture process (r-process) paths in the nuclear landscape is extremely challenging in nuclear physics and astrophysics. While various models predict similar proton drip line,…

Nuclear Theory · Physics 2015-10-22 Rui Wang , Lie-Wen Chen

We have made a parametric study of s-process nucleosynthesis in the metal poor ([Fe/H]=-2.7) stars LP625-44 and LP706-7. We find that a high neutron exposure and a small overlap factor are necessary to fit the abundance pattern observed in…