Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Cowan, J. J.; Sneden, Christopher; Lawler, J. E.; Hartog, E. A. Den; Collier, Jason

doi:10.1063/1.2905524

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…A subclass of these extremely metal-poor stars with [Fe/H]≈ 3 is strongly enhanced with elements such as Eu ([Eu/Fe]> 0.5). These stars show a heavy element pattern (56 Z < 83) which is in extraordinary agreement with the r-process contribution to the solar system abundances [29]. In addition, the abundance pattern in these stars is remarkably robust from star to star.…”

Section: Observational Constraintssupporting

confidence: 71%

Supernovae, neutrinos, and nucleosynthesis

Fröhlich¹

2014

J. Phys. G: Nucl. Part. Phys.

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Core-collapse supernovae are the violent explosions at the end of the life of massive stars (≳ 8 − 10 M⊙). In these explosions a wide range of elements are synthesized and ejected: low-mass elements (O and Mg) from the hydrostatic evolution, intermediate-mass elements and Fe-group elements from explosive nucleosynthesis, and elements heavier than iron from the νp-process and potentially an r-process. However, supernova nucleosynthesis predictions are hampered by the not yet fully understood supernova explosion mechanism. In addition, recent progress in observational astronomy paints a fascinating picture for the origin of heavy elements, which is more complicated than the traditional s-, r-, and γ-processes. In this paper, we summarize the status of core-collapse supernova nucleosynthesis.

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Section: Observational Constraintssupporting

confidence: 71%

Supernovae, neutrinos, and nucleosynthesis

Fröhlich¹

2014

J. Phys. G: Nucl. Part. Phys.

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“…We first use the classical approach to reproduce the solar r-pattern for 125 ≤ A ≤ 209 [57] (see also e.g., [55,58]), which is shown as the dashed curve in Fig. 5.…”

Section: A Comparison With Solar-like R-patternsmentioning

confidence: 99%

Reexamining the temperature and neutron density conditions forr-process nucleosynthesis with augmented nuclear mass models

Sun

Niu

et al. 2013

Phys. Rev. C

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We explore the effects of nuclear masses on the temperature and neutron density conditions required for r-process nucleosynthesis using four nuclear mass models augmented by the latest atomic mass evaluation. For each model we derive the conditions for producing the observed abundance peaks at mass numbers A ∼ 80, 130, and 195 under the waiting-point approximation and further determine the sets of conditions that can best reproduce the r-process abundance patterns (r-patterns) inferred for the solar system and observed in metal-poor stars of the Milky Way halo. In broad agreement with previous studies, we find that (1) the conditions for producing abundance peaks at A ∼ 80 and 195 tend to be very different, which suggests that at least for some nuclear mass models, these two peaks are not produced simultaneously; (2) the typical conditions required by the critical waiting-point (CWP) nuclei with the N = 126 closed neutron shell overlap significantly with those required by the N = 82 CWP nuclei, which enables coproduction of abundance peaks at A ∼ 130 and 195 in accordance with observations of many metal-poor stars; and (3) the typical conditions required by the N = 82 CWP nuclei can reproduce the r-pattern observed in the metal-poor star HD 122563, which differs greatly from the solar r-pattern. We also examine how nuclear mass uncertainties affect the conditions required for the r-process and identify some key nuclei including 76 Ni to 78 Ni, 82 Zn, 131 Cd, and 132 Cd for precise mass measurements at rare-isotope beam facilities.

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“…Because the specific astrophysical conditions among the different scenarios may change, solar r-process abundances [45] have been used in the past to constrain the astrophysical conditions using a site-independent approach [7,46]. In this approach seed-nuclei (usually the iron group) are irradiated by neutron sources of high and continuous neutron densities n n ranging from 10 20 to 10 28 cm −3 over a timescale τ in a high temperature environment (T ∼ 1GK).…”

Section: Site-independent R-process Approachmentioning

confidence: 99%

Application of the relativistic mean-field mass model to ther-process and the influence of mass uncertainties

et al. 2008

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A new mass table calculated by the relativistic mean field approach with the state-dependent BCS method for the pairing correlation is applied for the first time to study r-process nucleosynthesis. The solar r-process abundance is well reproduced within a waiting-point approximation approach. Using an exponential fitting procedure to find the required astrophysical conditions, the influence of mass uncertainty is investigated. R-process calculations using the FRDM, ETFSI-Q and HFB-13 mass tables have been used for that purpose. It is found that the nuclear physical uncertainty can significantly influence the deduced astrophysical conditions for the r-process site. In addition, the influence of the shell closure and shape transition have been examined in detail in the r-process simulations.

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Abundance Signatures in Halo Stars: Clues to Nucleosynthesis in the First Stars

Cited by 3 publications

References 14 publications

Supernovae, neutrinos, and nucleosynthesis

Supernovae, neutrinos, and nucleosynthesis

Reexamining the temperature and neutron density conditions forr-process nucleosynthesis with augmented nuclear mass models

Application of the relativistic mean-field mass model to ther-process and the influence of mass uncertainties

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