期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 767, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/767/2/L22
关键词
stars: abundances; stars: evolution; stars: interiors
资金
- NSF (Joint Institute for Nuclear Astrophysics
- JINA) [PHY 02-16783, PHY 09-22648]
- EU [MIRG-CT-2006-046520, 306901]
- STFC
- NSERC
- SNSF
- EuroGENESIS
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [0907919] Funding Source: National Science Foundation
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1007977] Funding Source: National Science Foundation
- Division Of Physics
- Direct For Mathematical & Physical Scien [1068192] Funding Source: National Science Foundation
- Science and Technology Facilities Council [PP/D000955/1, ST/J001384/1, PP/F000057/1, ST/G002355/1, ST/J000035/1] Funding Source: researchfish
- STFC [ST/J000035/1, ST/G002355/1, ST/J001384/1, PP/F000057/1, PP/D000955/1] Funding Source: UKRI
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 lowdensity 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 C-12(alpha,gamma)O-16 reaction relative to the rest of the alpha-capture chain at T > 3.5 x 10(8) 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 Ca-44/Ca-40 observed in the grains. This is due to the production of Ti-44 together with Ca-40 in the C/Si zone and/or to the strong depletion of Ca-40 by neutron captures.
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