PRODUCTION OF CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS

Pignatari, M.; Wiescher, M.; Timmes, F. X.; de Boer, R. J.; Thielemann, F.-K.; Fryer, C.; Heger, A.; Herwig, F.; Hirschi, R.

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.

Citation

Pignatari, M., Wiescher, M., Timmes, F. X., de Boer, R. J., Thielemann, F., Fryer, C., …Hirschi, R. (in press). 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

• Journal Article Type: Article
• Acceptance Date: Mar 8, 2013
• Online Publication Date: Apr 1, 2013
• Deposit Date: Jun 16, 2023
• Journal: The Astrophysical Journal
• Print ISSN: 2041-8205
• Electronic ISSN: 2041-8213
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 767
• Issue: 2
• Pages: L22
• DOI: https://doi.org/10.1088/2041-8205/767/2/l22
• Keywords: Space and Planetary Science; Astronomy and Astrophysics