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Light and intermediate nuclei as well as s-process elements have been detected in presolar grains and in evolved red giants. The abundances of some of these nuclei cannot be accounted for by canonical stellar models and require…

Astrophysics of Galaxies · Physics 2010-12-14 M. Busso , E. Maiorca , L. Magrini , S. Randich , S. Palmerini , S. Cristallo

In this paper we present a large-scale sensitivity study of reaction rates in the main component of the $s$ process. The aim of this study is to identify all rates, which have a global effect on the $s$ process abundance distribution and…

Solar and Stellar Astrophysics · Physics 2016-02-16 A. Koloczek , B. Thomas , J. Glorius , R. Plag , M. Pignatari , R. Reifarth , C. Ritter , S. Schmidt , K. Sonnabend

In order to get a broader view of the s-process nucleosynthesis we study the abundance distribution of heavy elements of 35 barium stars and 24 CEMP-stars, including nine CEMP-s stars and 15 CEMP-r/s stars. The similar distribution of…

Solar and Stellar Astrophysics · Physics 2013-05-09 Wenyuan Cui , Jianrong Shi , Yuanyuan Geng , Caixia Zhang , Xiaoying Meng , Lang Shao , Bo Zhang

Recent spectroscopic studies have revealed the presence of numerous carbon-enhanced, metal-poor stars with [Fe/H] < -2.0 that exhibit strong enhancements of s-process elements. These stars are believed to be the result of a binary…

Astrophysics · Physics 2009-11-13 S. Wanajo , K. Nomoto , N. Iwamoto , Y. Ishimaru , T. C. Beers

The rapid neutron capture or 'r process' of nucleosynthesis is believed to be responsible for the production of approximately half the natural abundance of heavy elements found on the periodic table above iron (with proton number $Z=26$)…

Nuclear Theory · Physics 2023-04-05 E. M. Holmbeck , T. M. Sprouse , M. R. Mumpower

New measurements of neutron-capture elements are presented for two very metal-poor stars ([Fe/H] ~ -3). One (LP 625-44) has an s-process signature believed to be due to mass transfer from a now-extinct metal-poor AGB companion, and the…

Neutron(n)-capture elements are produced by s-process nucleosynthesis in low- and intermediate-mass AGB stars, and therefore can be enriched in planetary nebulae (PNe). In the last ten years, n-capture elements have been detected in more…

Solar and Stellar Astrophysics · Physics 2017-11-15 N. C. Sterling

The rapid neutron-capture process, creating about half of the heaviest elements in the Solar System was believed to be unique. Many recent studies have shown that this does not include the formation of lighter elements (in particular 38 < Z…

S stars are transition objects between M-type giants and carbon stars on the asymptotic giant branch (AGB). They are characterized by overabundances of s-process elements. Roughly half of them are enhanced in technetium (Tc), an s-process…

Elements in the range 37 < Z < 47 provide key information on their formation process. Several studies have shown that some of these elements are formed by an r-process, that differs from the main r-process creating europium. Through a…

Solar and Stellar Astrophysics · Physics 2012-12-20 Camilla Juul Hansen

The astrophysical origin of the rapid neutron-capture process (r-process), which produces about half of the elements heavier than iron, remains uncertain. The oldest, most metal-poor stars preserve the chemical signatures of early…

The primary nature of the $^{13}$C neutron source is very significant for the studies of the s-process nucleosynthesis. In this paper we present an attempt to fit the element abundances observed in 16 s-rich stars using parametric model of…

Astrophysics · Physics 2008-11-26 Kun Ma , W. Y. Cui , B. Zhang

Asymptotic Giant Branch (AGB) stars play a fundamental role in the s-process nucleosynthesis during their thermal pulsing phase. The theoretical predictions obtained by AGB models at different masses, s-process efficiencies, dilution…

Solar and Stellar Astrophysics · Physics 2014-11-20 S. Bisterzo , R. Gallino , O. Straniero , W. Aoki

The existence of neutron star mergers has been supported since the discovery of the binary pulsar and the observation of its orbital energy loss, consistent with General Relativity. They are considered nucleosynthesis sites of the rapid…

High Energy Astrophysical Phenomena · Physics 2017-10-09 F. -K. Thielemann , M. Eichler , I. V. Panov , B. Wehmeyer

The chemical abundances of elements such as barium and the lanthanides are essential to understand the nucleosynthesis of heavy elements in the early Universe as well as the contribution of different neutron capture processes (for example…

Classical barium stars are red giants that received from their evolved binary companions material exposed to the \textit{slow} neutron-capture nucleosynthesis, i.e., the $s$-process. Such a mechanism is expected to have taken place in the…

Solar and Stellar Astrophysics · Physics 2024-01-18 M. P. Roriz , M. Lugaro , S. Junqueira , C. Sneden , N. Drake , C. B. Pereira

Metal-poor stars in the Galactic halo often show strong enhancements in carbon and/or neutron-capture elements. However, the Galactic bulge is notable for its paucity of carbon-enhanced metal-poor (CEMP) and/or CH-stars, with only two such…

Astrophysics of Galaxies · Physics 2019-02-13 A. Koch , M. Reichert , C. J. Hansen , M. Hampel , R. J. Stancliffe , A. Karakas , A. Arcones

Employing spectra obtained with the new Keck I HIRES near-UV sensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS29497-030. Abundances for 29 elements and upper limits for…

The observational data guiding the theoretical chemical evolutionary models of AGB stars come mainly from the analysis of intrinsic and extrinsic s-process enriched objects. The first are the stars of the M-MS-S-SC-C star sequence which is…

Astrophysics · Physics 2007-05-23 M. Reyniers , H. Van Winckel

The very metal-poor star HE 0338-3945 shows a double-enhanced pattern of the neutron-capture elements. The study to this sample could make people gain a better understanding of s- and r-process nucleosynthesis at low metallicity. Using a…

Solar and Stellar Astrophysics · Physics 2010-10-22 Wenyuan Cui , Jiang Zhang , Zizhong Zhu , Bo Zhang