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Efficient mixing of the solar nebula from uniform Mo isotopic composition of meteorites

机译：由陨石的均匀Mo同位素组成有效混合太阳云

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摘要

The abundances of elements and their isotopes in our Galaxy show wide variations, reflecting different nucleosynthetic processes in stars and the effects of Galactic evolution. These variations contrast with the uniformity of stable isotope abundances for many elements in the Solar System, which implies that processes efficiently homogenized dust and gas from different stellar sources within the young solar nebula. However, isotopic heterogeneity has been recognized on the subcentimetre scale in primitive meteorites, indicating that these preserve a compositional memory of their stellar sources. Small differences in the abundance of stable molybdenum isotopes in bulk rocks of some primitive and differentiated meteorites, relative to terrestrial Mo, suggest large-scale Mo isotopic heterogeneity between some inner Solar System bodies, which implies physical conditions that did not permit efficient mixing of gas and dust. Here we report Mo isotopic data for bulk samples of primitive and differentiated meteorites that show no resolvable deviations from terrestrial Mo. This suggests efficient mixing of gas and dust in the solar nebula at least to 3 AU from the Sun, possibly induced by magnetohydrodynamic instabilities. These mixing processes must have occurred before isotopic fractionation of gas-phase elements and volatility-controlled chemical fractionations were established.
机译：我们银河系中的元素及其同位素的丰度表现出很大的差异，反映了恒星中不同的核合成过程以及银河系演化的影响。这些变化与太阳系中许多元素的稳定同位素丰度的均匀性形成对比，这意味着过程可以有效地使来自年轻太阳星云中不同恒星源的尘埃和气体均匀化。然而，在原始陨石的亚尺度范围内已经认识到同位素异质性，表明这些陨石保留了其恒星来源的组成记忆。相对于陆地Mo，一些原始的和分化的陨石的块状岩石中稳定的钼同位素的丰度与地面Mo的微小差异表明，某些太阳系内部天体之间存在大规模的Mo同位素异质性，这意味着不允许有效混合气体的物理条件和灰尘。在这里，我们报告了原始和分化的陨石的大量样品的Mo同位素数据，这些样品未显示出与地面Mo的可分辨偏差。这表明太阳星云中的气体和尘埃有效混合，至少距太阳3 AU，这可能是由磁流体动力不稳定性引起的。这些混合过程必须在气相元素的同位素分馏和挥发性控制的化学分馏建立之前就已经发生。

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  • 来源
    《Nature》 |2003年第6954期|p.152-155|共4页
  • 作者

    Harry Becker; Richard J. Walker;

  • 作者单位

    Department of Geology, University of Maryland, College Park, Maryland 20742, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
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