早期太阳系中的萨马-146:来自艾伦德石中的底的证据
概括
研究人员在一颗石中发现了显著的新同位素丰富,可能来自萨马衰变. 这表明太阳系早期的萨马-146的初始丰度更高,这可能对约会有用.
科学领域:
- 宇宙化学 宇宙化学
- 同位素地球化学 同位素地球化学
- 行星科学 行星科学
背景情况:
- 石,如石,是太阳系早期的残余物,为其形成和演变提供了洞察力.
- 石中的同位素异常可以表明早期太阳系中存在短寿命放射性同位素.
- 撒马-146 (半衰期1.08亿年) 是一个现已灭绝的同位素,与早期太阳系核合成和时间表有关.
研究的目的:
- 为了研究在阿伦德石的碳化物部分中观察到的新-142和新-143的大型同位素丰富的起源.
- 为了确定早期太阳系中灭绝的萨马-146的初始丰度.
- 评估-同位素系统作为早期太阳系事件的计时器的潜力.
主要方法:
- 来自阿伦德C3V混岩的碳化物部分的分析.
- 测量新同位素丰富物 (新-142和新-143).
- 考虑到萨马-146和萨马-147的α衰变以及核反弹效应,对同位素丰富的建模.
主要成果:
- 在分析样本中观察到显著的新-142 (0.47%) 和新-143 (36%) 的同位素丰富.
- 将这些缩归因于已灭绝的萨马-146和长寿的萨马-147.的α衰变.
- 证明核反弹将同位素丰富放大到周围的碳膜中.
- 提供了对萨马-146的初始丰度的改进估计: (146) Sm/(144) Sm = (4.5 ± 0.5) x 10−3.3.
- 这种丰富度高于一些核合成模型所预测的.
结论:
- 观察到的同位素异常与通过撒马衰变形成一致,由核反弹显著增强.
- 估计的萨马-146的初始丰度高于以前建模的,影响我们对早期太阳系核合成的理解.
- -同位素对有潜力作为一个有价值的计时器来测定太阳系早期事件的年代.
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