Precise initial abundance of Niobium-92 in the Solar System and implications for p-process nucleosynthesis
Precise initial abundance of Niobium-92 in the Solar System and implications for p-process nucleosynthesis
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太阳系中 Niobium-92 的精确初始丰度及其对 p 过程核合成的影响
DOI：
10.1073/pnas.2017750118
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Schonbachler Maria
中科院分区：
文献类型：
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作者：
Haba Makiko K.;Lai Yi-Jen;Wotzlaw Jorn-Frederik;Yamaguchi Akira;Lugaro Maria;Schonbachler Maria
铌-92-锆-92（92 Nb-92 Zr）衰变系统的半衰期为37 Ma，在确定早期太阳系行星物质演化的年代方面具有很大的潜力。此外，太阳系中p过程同位素92 Nb的初始丰度对于在天体物理模型中量化p过程核合成的贡献是重要的。目前对92 Nb/93 Nb初始比值的估计有很大的不确定性，影响了92 Nb-92 Zr宇宙计时器的使用，使核合成模型受到很大的限制。本文通过对同生金红石和锆石的~（92）Nb-~（92）Zr系统学研究，结合锆石U-Pb定年，高精度地确定了92 Nb初始丰度。矿物对表明太阳系的92 Nb/93 Nb比值起始于（1.66 ± 0.10）× 10−5，而它们的92 Zr/90 Zr比值可以用中陨铁母体上Nb-Zr的三阶段演化来解释。由于92 Nb/93 Nb的精度比太阳系初期提高了6倍，我们可以证明，在早期太阳系中92 Nb的存在进一步证明了Ia型超新星和核心坍缩超新星对轻p过程核的贡献。
The niobium-92–zirconium-92 (92Nb–92Zr) decay system with a half-life of 37 Ma has great potential to date the evolution of planetary materials in the early Solar System. Moreover, the initial abundance of thep-process isotope92Nb in the Solar System is important for quantifying the contribution ofp-process nucleosynthesis in astrophysical models. Current estimates of the initial92Nb/93Nb ratios have large uncertainties compromising the use of the92Nb–92Zr cosmochronometer and leaving nucleosynthetic models poorly constrained. Here, the initial92Nb abundance is determined to high precision by combining the92Nb–92Zr systematics of cogenetic rutiles and zircons from mesosiderites with U–Pb dating of the same zircons. The mineral pair indicates that the92Nb/93Nb ratio of the Solar System started with (1.66 ± 0.10) × 10−5, and their92Zr/90Zr ratios can be explained by a three-stage Nb–Zr evolution on the mesosiderite parent body. Because of the improvement by a factor of 6 of the precision of the initial Solar System92Nb/93Nb, we can show that the presence of92Nb in the early Solar System provides further evidence that both type Ia supernovae and core-collapse supernovae contributed to the lightp-process nuclei.