Abstract

This contribution presents an extension of our r-process parameter study within the high-entropy-wind (HEW) scenario of corecollapse supernovae (ccSNe). One of the primary aims of this study was to obtain indications for the production of classical p-, s- and r-isotopes of the light trans-Fe elements in the Solar System (S.S.). Here, we focus on the nucleosynthesis origin of the anomalous isotopic compositions of Zr, Mo and Ru in presolar SiC X-grains (SNe grains). In contrast to the interpretation of other groups, we show that these grains do not represent the signatures of a ‘clean’ stellar scenario, but rather, are mixtures of an exotic nucleosynthesis component and S.S. material. We further confirm the results of our earlier studies whereby sizeable amounts of all stable p-, s- and r-isotopes of Zr, Mo and Ru can be co-produced by moderately neutron-rich ejecta of the low-entropy, charged-particle scenario of ccSNe (type II). The synthesis of these isotopes through a ‘primary’ production mode provides further means to revise the abundance estimates of the light trans-Fe elements from so far favoured ‘secondary’ scenarios like Type Ia SNe or neutron-bursts in exploding massive stars.

Highlights

  • The nucleosynthetic origin of the stable isotopes in the light trans-Fe region between Zn (Z = 30) and Ru (Z = 44) in the Solar System (S.S.) has been a fascinating subject for astrophysicists, astronomers, nuclear chemists and physicists, and cosmochemists for over 60 years [1 - 3]

  • It is commonly believed that these elements are produced by various contributions from three different historical stellar processes: (i) the ‘p-process’ [4, 5], (ii) the ‘weak s-process’ ([6, 7] and refs. therein), and (iii) the ‘weak r-process’ ([8 - 10] and refs. therein)

  • We offer a solution to these problems by following up on our earlier preliminary results [28, 29] exploring the ‘primary’ production of the light trans-Fe elements in a classical core-collapse supernova, low-entropy, neutrino-driven-wind scenario

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Summary

Introduction

The nucleosynthetic origin of the stable isotopes in the light trans-Fe region between Zn (Z = 30) and Ru (Z = 44) in the Solar System (S.S.) has been a fascinating subject for astrophysicists, astronomers, nuclear chemists and physicists, and cosmochemists for over 60 years [1 - 3] In this multidisciplinary community, it is commonly believed that these elements are produced by various contributions from three different historical stellar processes: (i) the ‘p-process’ [4, 5], (ii) the ‘weak s-process’ The interpretation of the anomalous Zr, Mo and Ru isotope compositions of SiC-X grains have so far defied a straightforward p-, s- or r-process explanation, requiring alternate nucleosynthesis scenarios One such favoured process for the production of these light trans-Fe elements is the ‘secondary’ (i.e. metallicity dependant) neutron-burst (n-burst) occurring in the shocked He-shell of exploding massive stars [25 - 27]. We offer a solution to these problems by following up on our earlier preliminary results [28, 29] exploring the ‘primary’ production of the light trans-Fe elements in a classical core-collapse supernova (ccSN), low-entropy, neutrino-driven-wind scenario

Theory
Observations: presolar silicon carbide-X grains
Searching for the stellar source of SiC-X grains
Conclusions
Full Text
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