Pignatari, Marco and Zinner, E. and Bertolli, M. G. and Trappitsch, R. and Hoppe, P. and Rauscher, T. and Fryer, C. and Herwig, F. and Hirschi, R. and Timmes, F. X. and Thielemann, F. -K (2013) Silicon carbide grains of type C provide evidence for the production of the unstable isotope 32Si in supernovae. ASTROPHYSICAL JOURNAL, 771 (1). ISSN 1538-4357
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Abstract
Carbon-rich grains are observed to condense in the ejecta of recent core-collapse supernovae, within a year after the explosion. Silicon carbide grains of type X are C-rich grains with isotpic signatures of explosive supernova nucleosynthesis have been found in primitive meteorites. Much rarer silicon carbide grains of type C are a special sub-group of SiC grains from supernovae. They show peculiar abundance signatures for Si and S, isotopically heavy Si and isotopically light S, which appear to to be in disagreement with model predictions. We propose that C grains are formed mostly from C-rich stellar material exposed to lower SN shock temperatures than the more common type X grains. In this scenario, extreme 32S enrichments observed in C grains may be explained by the presence of short-lived 32Si (τ 1/2 = 153 years) in the ejecta, produced by neutron capture processes starting from the stable Si isotopes. No mixing from deeper Si-rich material and/or fractionation of Si from S due to molecular chemistry is needed to explain the 32S enrichments. The abundance of 32Si in the grains can provide constraints on the neutron density reached during the supernova explosion in the C-rich He shell material. The impact of the large uncertainty of the neutron capture cross sections in the 32Si region is discussed.
Item Type: | Article |
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Uncontrolled Keywords: | stars: evolution; stars: abundances; stars: interiors; stars: massive; |
Subjects: | Q Science / természettudomány > QB Astronomy, Astrophysics / csillagászat, asztrofizika |
SWORD Depositor: | MTMT SWORD |
Depositing User: | MTMT SWORD |
Date Deposited: | 16 Aug 2024 10:27 |
Last Modified: | 16 Aug 2024 10:27 |
URI: | https://real.mtak.hu/id/eprint/202735 |
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