| SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE | |
| Yuchen Xu; Ernst Zinne; Roberto Gallino; Alexander Heger; Marco Pignatari; Yangting Lin | |
| 2015 | |
| Source Publication | The Astrophysical Journal
 |
| Volume | 799Issue:2 |
| Abstract | We report C, Si, N, S, Mg-Al, and Ca-Ti isotopic compositions of presolar silicon carbide (SiC) grains from the SiC-rich KJE size fraction (0.5-0.8 m) of the Murchison meteorite. One thousand one hundred thirteen SiC grains were identified based on their C and Si isotopic ratios. Mainstream, AB, C, X, Y, and Z subtypes of SiC, and X-type silicon nitride (Si3N4) account for 81.4%, 5.7%, 0.1%, 1.5%, 5.8%, 4.9%, and 0.4%, respectively. Twenty-five grains with unusual Si isotopic ratios, including one C grain, 16 X grains, 1 Y grain, 5 Z grains, and 2 X-type Si3N4 grains were selected for N, S, Mg-Al, and Ca-Ti isotopic analysis. The C grain is highly enriched in 29Si and 30Si (d29Si = 1345% 19%, d30Si = 1272% 19%). It has a huge 32S excess, larger than any seen before, and larger than that predicted for the Si/S supernova (SN) zone, providing evidence against the elemental fractionation model by Hoppe et al. Two SN models investigated here present a more satisfying explanation in terms of a radiogenic origin of 32S from the decay of short-lived 32Si (t 1/2 = 153 yr). Silicon-32 as well as 29Si and 30Si can be produced in SNe by short neutron bursts; evidence for initial 44Ti (t 1/2 = 60 yr) in the C grain is additional evidence for an SN origin. The X grains have marginal 32S excesses, much smaller than expected from their large 28Si excesses. Similarly, the Y and Z grains do not show the S-isotopic anomalies expected from their large Si isotopic anomalies. Low intrinsic S contents and contamination with isotopically normal S are the most likely explanations. |
| Subject Area | 环境地球化学 |
| Indexed By | SCI |
| Language | 英语 |
| Document Type | 期刊论文 |
| Identifier | http://ir.gyig.ac.cn/handle/352002/5990 |
| Collection | 环境地球化学国家重点实验室_环境地球化学国家重点实验室_期刊论文 |
| Recommended Citation GB/T 7714 | Yuchen Xu,Ernst Zinne,Roberto Gallino,et al. SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE[J]. The Astrophysical Journal,2015,799(2). |
| APA | Yuchen Xu,Ernst Zinne,Roberto Gallino,Alexander Heger,Marco Pignatari,&Yangting Lin.(2015).SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE.The Astrophysical Journal,799(2). |
| MLA | Yuchen Xu,et al."SULFUR ISOTOPIC COMPOSITIONS OF SUBMICROMETER SiC GRAINS FROM THE MURCHISON METEORITE".The Astrophysical Journal 799.2(2015). |
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