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  • ASTROPHYSICS  (1)
  • LUNAR AND PLANETARY EXPLORATION  (1)
  • 1990-1994  (2)
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  • ASTROPHYSICS  (1)
  • LUNAR AND PLANETARY EXPLORATION  (1)
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  • 1990-1994  (2)
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  • 1
    Publication Date: 2019-08-28
    Description: We show that the high-temperature, high-entropy evacuated region outside the recent neutron star in a core-collapse supernova may be an ideal r-process site. In this high-entropy environment it is possible that most nucleons are in the form of free neutrons or bound into alpha particles. Thus, there can be many neutrons per seed nucleus even though the material is not particularly neutron rich. The predicted amount of r-process material ejected per event from this environment agrees well with that required by simple galactic evolution arguments. When averaged over regions of different neutron excess in the supernova ejecta, the calculated r-process abundance curve can give a good representation of the solar-system r-process abundances as long as the entropy per baryon is sufficiently high. Neutrino irradiation may aid in smoothing the final abundance distribution.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 399; 2; p. 656-664.
    Format: text
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  • 2
    Publication Date: 2019-08-28
    Description: We examine quantitatively the suggestion that the heavy anomalous isotopes of Xe-HL found in meteoritic diamonds were produced by a short intense neutron burst and then implanted into the diamonds. Using a large nuclear reaction network we establish one (out of many) neutron irradiation hostories that successfully reproduces the heavy isotopes of Xe-HL, and then evaluate what that same history would produce in every heavy element. This has become more relevant following recent measurement of anomalous Ba and Sr in those same diamond samples. Therefore we offer these calculations as a guide to the anomalies to be expected in all elements if this scenario is correct. We also discuss several other aspects of the problem, especially the established contradictions for Ba, the observed Kr pattern, the near normalcy of Xe-129 and some related astrophysical ideas. In particular we argue from p-process theory that the observed deficit of Kr-78 in correlation with Xe-(124-126) excess implicates Type II supernovae as the diamond sources.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Meteoritics (ISSN 0026-1114); 27; 4; p. 404-412.
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