Murchison陨石酸性浸出液中的核合成锇同位素异常
Nucleosynthetic osmium isotope anomalies in acid leachates of the Murchison meteorite
摘要：
我们提出了锇同位素的Murchison陨石，这揭示了存在非常大的内部异常的核合成起源的顺序浸出获得的结果。Os同位素异常是相关的，可以解释的变量的贡献来自核合成的s，r和p-过程的组件。大部分的S-过程丰富的锇是通过相对温和的浸出释放，这表明存在一个容易浸出的S-过程丰富的presolar相，或者替代地，化学抗性的R-过程丰富的相。由温和的浸出释放的Os的S-过程组合物略有偏离，从积极的消化技术，也许表明这些不同的程序在不同的恒星环境中凝聚的前太阳相攻击。1900 s和1880 s之间的相关性可用于将s-过程1900 s/1880 s比率约束为1.275pm 0.043。这样的比率可以在核反应网络中重现，在30 keV下，190 Os的MACS值为~200 pm 22 mbarn。我们还提出了证据，广泛的内部变化的184 Os丰度的默奇森陨石。这表明p处理丰富的前太阳粒（例如，超新星凝聚物）可能存在于陨石中，其数量足以影响浸出物的Os同位素组成。
英文摘要：
We present osmium isotopic results obtained by sequential leaching of the Murchison meteorite, which reveal the existence of very large internal anomalies of nucleosynthetic origin. The Os isotopic anomalies are correlated, and can be explained by the variable contributions of components derived from the s, r and p-processes of nucleosynthesis. Much of the s-process rich osmium is released by relatively mild leaching, suggesting the existence of an easily leachable s-process rich presolar phase, or alternatively, of a chemically resistant r-process rich phase. The s-process composition of Os released by mild leaching diverges slightly from that released by aggressive digestion techniques, perhaps suggesting that the presolar phases attacked by these differing procedures condensed in different stellar environments. The correlation between 190Os and 188Os can be used to constrain the s-process 190Os/188Os ratio to be 1.275 pm 0.043. Such a ratio can be reproduced in a nuclear reaction network for a MACS value for 190Os of ~200 pm 22 mbarn at 30 keV. We also present evidence for extensive internal variation of 184Os abundances in the Murchison meteorite. This suggests that p process rich presolar grains (e.g., supernova condensates) may be present in meteorites in sufficient quantities to influence the Os isotopic compositions of the leachates.
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