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.-K., Fryer, C., Heger, A., Herwig, F., & 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
• Public URL: https://keele-repository.worktribe.com/output/471183