SULFUR MOLECULE CHEMISTRY IN SUPERNOVA EJECTA RECORDED BY SILICON CARBIDE STARDUST
SULFUR MOLECULE CHEMISTRY IN SUPERNOVA EJECTA RECORDED BY SILICON CARBIDE STARDUST
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DOI：
10.1088/2041-8205/745/2/l26
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发表时间：
2012-02-01
影响因子：
7.9
通讯作者：
Zinner, Ernst
中科院分区：
文献类型：
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作者：
Hoppe, Peter;Fujiya, Wataru;Zinner, Ernst
我们研究了约3400 presolar碳化硅（SiC）颗粒从默奇森CM 2陨石的C-和Si-同位素组成。在这些颗粒中，我们确定了7个不寻常的或C型SiC（U/C）颗粒，其特征在于同位素重Si，和36个超新星X型SiC颗粒，其特征在于同位素轻Si。还测量了选定的U/C和X晶粒的S-，Mg-Al-和Ca-Ti-同位素组成。我们发现U/C颗粒中含有放射性Ti-44，这证明它们是在II型超新星（SNII）爆炸的喷出物中形成的。放射性Al-26和Ti-44的丰度与在X晶粒中观察到的一致。U/C和X颗粒携带轻硫，S-32富集高达2.7倍。在U/C颗粒中观察到的重Si和轻S的组合与简单超新星模型的丰度预测不一致。同位素数据表明，S从最里面的超新星区，放射性Ti-44的生产现场，由不断增长的碳化硅颗粒优先捕获。实现这一目标的一种方法是通过仍未混合的喷出物中的硫分子化学。这证实了SNII喷出物中分子形成的模型预测，并表明硫分子化学在恒星爆炸的恶劣和炎热的环境中运作。
We studied about 3400 presolar silicon carbide (SiC) grains from the Murchison CM2 meteorite for C- and Si-isotopic compositions. Among these grains we identified 7 unusual or type C SiC (U/C) grains, characterized by isotopically heavy Si, and 36 supernova type X SiC grains, characterized by isotopically light Si. Selected U/C and X grains were also measured for S-, Mg-Al-, and Ca-Ti-isotopic compositions. We show that the U/C grains incorporated radioactive Ti-44, which is evidence that they formed in the ejecta of Type II supernova (SNII) explosions. Abundances of radioactive Al-26 and Ti-44 are compatible with those observed in X grains. U/C and X grains carry light S with enrichments in S-32 of up to a factor of 2.7. The combination of heavy Si and light S observed in U/C grains is not consistent with abundance predictions of simple supernova models. The isotope data suggest preferential trapping of S from the innermost supernova zones, the production site of radioactive Ti-44, by the growing silicon carbide particles. A way to achieve this is by sulfur molecule chemistry in the still unmixed ejecta. This confirms model predictions of molecule formation in SNII ejecta and shows that sulfur molecule chemistry operates in the harsh and hot environments of stellar explosions.