Three-dimensional Supernova Models Provide New Insights into the Origins of Stardust

Abstract

We present the isotope yields of two post-explosion, three-dimensional 15 $M_{\odot }$ core-collapse supernova models, 15S and 15A, and compare them to the carbon, nitrogen, silicon, aluminum, sulfur, calcium, titanium, iron, and nickel isotopic compositions of SiC stardust. We find that these core-collapse supernova models predict similar carbon and nitrogen compositions to SiC X grains and grains with ${}^{12}$C/${}^{13}$C $<$ 20 and ${}^{14}$N/${}^{15}$N $<$ 60, which we will hereafter refer to as SiC 'D' grains. Material from the interior of a 15 $M_{\odot }$ explosion reaches high enough temperatures shortly after core collapse to produce the large enrichments of ${}^{13}$C and ${}^{15}$N necessary to replicate the compositions of SiC D grains. The innermost ejecta in a core-collapse supernova is operating in the neutrino-driven regime and undergoes fast proton capture after being heated by the supernova shockwave. Both 3-D models predict 0.3 $<$ ${}^{26}$Al/${}^{27}$Al $<$ 1.5, comparable to the ratios seen in SiC X, C, and D grains. Models 15S and 15A, in general, predict very large anomalies in calcium isotopes but do compare qualitatively with the SiC X grain measurements that show ${}^{44}$Ca and ${}^{43}$Ca excesses. The titanium isotopic compositions of SiC X grains are well reproduced. The models predict ${}^{57}$Fe excesses and depletions that are observed in SiC X grains, and in addition predict accurately the ${}^{60}$Ni/${}^{58}$Ni, ${}^{61}$Ni/${}^{58}$Ni, and ${}^{62}$Ni/${}^{58}$Ni ratios in SiC X grains, as a result of fast neutron captures initiated by the propagation of the supernova shockwave. Finally, symmetry has a noticeable effect on the production of silicon, sulfur, and iron isotopes in the SN ejecta.

18 pages and 7 figures. Figures shown at the end. Accepted for publication in ApJ

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