Production of carbon-rich presolar grains from massive stars

M. Pignatari, M. Wiescher, Francis Timmes, R. J. De Boer, F. K. Thielemann, C. Fryer, A. Heger, F. Herwig, R. Hirschi

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26 Scopus citations

Abstract

About a year after core-collapse supernova, dust starts to condense in the ejecta. In meteorites, a fraction of C-rich presolar grains (e.g., silicon carbide (SiC) grains of Type-X and low density graphites) are identified as relics of these events, according to the anomalous isotopic abundances. Several features of these abundances remain unexplained and challenge the understanding of core-collapse supernovae explosions and nucleosynthesis. We show, for the first time, that most of the measured C-rich grain abundances can be accounted for in the C-rich material from explosive He burning in core-collapse supernovae with high shock velocities and consequent high temperatures. The inefficiency of the 12C(α, γ)16O reaction relative to the rest of the α-capture chain at T > 3.5 × 108 K causes the deepest He-shell material to be carbon-rich and silicon-rich, and depleted in oxygen. The isotopic ratio predictions in part of this material, defined here as the C/Si zone, are in agreement with the grain data. The high-temperature explosive conditions that our models reach at the bottom of the He shell can also be representative of the nucleosynthesis in hypernovae or in the high-temperature tail of a distribution of conditions in asymmetric supernovae. Finally, our predictions are consistent with the observation of large 44Ca/40Ca observed in the grains. This is due to the production of 44Ti together with 40Ca in the C/Si zone and/or to the strong depletion of 40Ca by neutron captures.

Original languageEnglish (US)
Article numberL22
JournalAstrophysical Journal Letters
Volume767
Issue number2
DOIs
StatePublished - Apr 20 2013

Keywords

  • stars: abundances
  • stars: evolution
  • stars: interiors

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Pignatari, M., Wiescher, M., Timmes, F., De Boer, R. J., Thielemann, F. K., Fryer, C., Heger, A., Herwig, F., & Hirschi, R. (2013). Production of carbon-rich presolar grains from massive stars. Astrophysical Journal Letters, 767(2), [L22]. https://doi.org/10.1088/2041-8205/767/2/L22