Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta
Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta
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在富含气体的陨石 Kapoeta 中观察到与太空风化相关的富质子核同位素过量
DOI：
10.1088/0004-637x/786/2/138
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
H. Hidaka and S. Yoneda
中科院分区：
文献类型：
--
作者：
Miyashita;Y.;A. Ieda;S. Machida;Y. Hiraki;V. Angelopoulos;J. P. McFadden;H. U. Auster;S. B. Mende;E. Donovan;and D. Larson;H. Hidaka and S. Yoneda
太阳系物质被早期太阳的太阳宇宙射线辐射的观点早就提出了，但仍然值得怀疑。本研究测定了Kapoeta陨石（howardite）序列酸浸出液的Sr、Ba、Ce、Nd、Sm和Gd同位素组成，发现其富质子核同位素丰度的系统和相关变化，从而了解宇宙射线辐照条件。富质子同位素（p-同位素）84sr、130ba、132ba、136ce、138ce和144sm明显过量，特别是在第一次化学分离中，可能在离样品表层几μm的极浅层中浸出。结果表明，在卡波埃塔陨石母体形成之前，太阳宇宙射线与表层风化粒的相互作用产生了p同位素，表明早期太阳活动强烈。
The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), 84 Sr, 130 Ba, 132 Ba, 136 Ce, 138 Ce, and 144 Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.