s-Processing in Asymptotic Giant Branch Stars in the Light of Revised Neutron-Capture Cross Sections

Vescovi, D.; Reifarth, R.

doi:10.3390/universe7070239

Cited by 3 publications

(2 citation statements)

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“…Recent research on nuclear cross-sections, on the other hand, pointed out that substantial work is still needed in that field, both through real new estimates and through reanalysis of existing datasets (e.g., by Monte Carlo techniques) (Reifarth et al, 2018). Partial results from this work have recently been used (Vescovi and Reifarth, 2021) to study the impact on nuclear upgrades in stellar models. So far, however, a global update of the Kadonis compilation is still waited for.…”

Section: A Model For Slow Neutron Captures and Its Resultsmentioning

confidence: 99%

Production of solar abundances for nuclei beyond Sr: The s- and r-process perspectives

Busso

Kratz

Palmerini

et al. 2022

Front. Astron. Space Sci.

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We present the status of nucleosynthesis beyond Sr, using up-to-date nuclear inputs for both the slow (s-process) and rapid (r-process) scenarios of neutron captures. It is now widely accepted that at least a crucial part of the r-process distribution is linked to neutron star merger (NSM) events. However, so far, we have found only a single direct observation of such a link, the kilonova GW170817. Its fast evolution could not provide strict constraints on the nucleosynthesis details, and in any case, there remain uncertainties in the local r-process abundance patterns, which are independent of the specific astrophysical site, being rooted in nuclear physics. We, therefore, estimate the contributions from the r-process to solar system (S.S.) abundances by adopting the largely site-independent waiting-point concept through a superposition of neutron density components normalized to the r-abundance peaks. Nuclear physics inputs for such calculations are understood only for the trans-Fe nuclei; hence, we restrict our computations to the Sr–Pr region. We then estimate the s-process contributions to that atomic mass range from recent models of asymptotic giant branch stars, for which uncertainties are known to be dominated by nuclear effects. The outcomes from the two independent approaches are then critically analyzed. Despite the remaining problems from both sides, they reveal a surprisingly good agreement, with limited local discrepancies. These few cases are then discussed. New measurements in ionized plasmas are suggested as a source of improvement, with emphasis on β-decays from unstable Cs isotopes. For heavier nuclei, difficulties grow as r-process progenitors lie far off experimental reach and poorly known branchings affect s-processing. This primarily concerns nuclei that are significantly long-lived in the laboratory and have uncertain decay rates in stars, e.g., Lu176 and Re187. New measurements are urgently needed for them, too.

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Section: A Model For Slow Neutron Captures and Its Resultsmentioning

confidence: 99%

Production of solar abundances for nuclei beyond Sr: The s- and r-process perspectives

Busso

Kratz

Palmerini

et al. 2022

Front. Astron. Space Sci.

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“…For the 7 Be electron-capture rate, we use that computed by Simonucci et al [63] and provided in the tabulated form by Vescovi et al [64]. The effects induced by the adoption of further re-evaluated neutron-capture cross-sections, as provided by Reifarth et al [65], on the s-process nucleosynthesis in low-mass AGB stars has been recently investigated in the context of FRUITY models [66]. 75 Ge [91] 174 Yb(n, γ) 175 Yb [116] 207 Pb(n, γ) 208 Pb [137] 76 Ge(n, γ) 77 Ge [91] 176 Yb(n, γ) 177 Yb [116] 209 Bi(n, γ) 210 Bi [138] By using the aforementioned choices for the opacity tables, EOS, and nuclear reaction rates, we computed a standard solar model (for more details on the followed procedure see Vescovi et al [64,139]) to extract the initial solar helium and metallicity abundances, that are Y = 0.267 and Z = 0.0167, respectively.…”

Section: Input Physicsmentioning

confidence: 99%

Mixing and Magnetic Fields in Asymptotic Giant Branch Stars in the Framework of FRUITY Models

Vescovi¹

2021

Universe

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In the last few years, the modeling of asymptotic giant branch (AGB) stars has been much investigated, both focusing on nucleosynthesis and stellar evolution aspects. Recent advances in the input physics required for stellar computations made it possible to construct more accurate evolutionary models, which are an essential tool to interpret the wealth of available observational and nucleosynthetic data. Motivated by such improvements, the FUNS stellar evolutionary code has been updated. Nonetheless, mixing processes occurring in AGB stars’ interiors are currently not well-understood. This is especially true for the physical mechanism leading to the formation of the 13C pocket, the major neutron source in low-mass AGB stars. In this regard, post-processing s-process models assuming that partial mixing of protons is induced by magneto-hydrodynamics processes were shown to reproduce many observations. Such mixing prescriptions have now been implemented in the FUNS code to compute stellar models with fully coupled nucleosynthesis. Here, we review the new generation of FRUITY models that include the effects of mixing triggered by magnetic fields by comparing theoretical findings with observational constraints available either from the isotopic analysis of trace-heavy elements in presolar grains or from carbon AGB stars and Galactic open clusters.

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Origin of the elements

Arcones

Thielemann

2022

Astron Astrophys Rev

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What is the origin of the oxygen we breathe, the hydrogen and oxygen (in form of water H2O) in rivers and oceans, the carbon in all organic compounds, the silicon in electronic hardware, the calcium in our bones, the iron in steel, silver and gold in jewels, the rare earths utilized, e.g. in magnets or lasers, lead or lithium in batteries, and also of naturally occurring uranium and plutonium? The answer lies in the skies. Astrophysical environments from the Big Bang to stars and stellar explosions are the cauldrons where all these elements are made. The papers by Burbidge (Rev Mod Phys 29:547–650, 1957) and Cameron (Publ Astron Soc Pac 69:201, 1957), as well as precursors by Bethe, von Weizsäcker, Hoyle, Gamow, and Suess and Urey provided a very basic understanding of the nucleosynthesis processes responsible for their production, combined with nuclear physics input and required environment conditions such as temperature, density and the overall neutron/proton ratio in seed material. Since then a steady stream of nuclear experiments and nuclear structure theory, astrophysical models of the early universe as well as stars and stellar explosions in single and binary stellar systems has led to a deeper understanding. This involved improvements in stellar models, the composition of stellar wind ejecta, the mechanism of core-collapse supernovae as final fate of massive stars, and the transition (as a function of initial stellar mass) from core-collapse supernovae to hypernovae and long duration gamma-ray bursts (accompanied by the formation of a black hole) in case of single star progenitors. Binary stellar systems give rise to nova explosions, X-ray bursts, type Ia supernovae, neutron star, and neutron star–black hole mergers. All of these events (possibly with the exception of X-ray bursts) eject material with an abundance composition unique to the specific event and lead over time to the evolution of elemental (and isotopic) abundances in the galactic gas and their imprint on the next generation of stars. In the present review, we want to give a modern overview of the nucleosynthesis processes involved, their astrophysical sites, and their impact on the evolution of galaxies.

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s-Processing in Asymptotic Giant Branch Stars in the Light of Revised Neutron-Capture Cross Sections

Cited by 3 publications

References 58 publications

Production of solar abundances for nuclei beyond Sr: The s- and r-process perspectives

Production of solar abundances for nuclei beyond Sr: The s- and r-process perspectives

Mixing and Magnetic Fields in Asymptotic Giant Branch Stars in the Framework of FRUITY Models

Origin of the elements

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