Condensation in supernova ejecta and isotopic anomalies in meteorites
Condensation in supernova ejecta and isotopic anomalies in meteorites
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超新星喷射物中的凝结和陨石中的同位素异常
DOI：
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
L. Grossman
中科院分区：
文献类型：
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作者：
J. Lattimer;D. Schramm;L. Grossman
一些在陨石中观察到的同位素异常可能是由于超新星爆炸产生的前太阳颗粒。这一假设进行化学平衡冷凝计算的压力和成分，可能是适当的冷却超新星喷出物。前超新星星星被认为有一个“洋葱皮”的外观，不同的层是由于连续的静态核燃烧阶段。在超新星爆发期间，这些层中的每一层都经历了爆炸性核合成。由此产生的化学和同位素组成的每一层进行了讨论。然后对每一层进行化学凝聚计算，对于几个不同的总压值，C/O比，以及对于爆炸氧燃烧壳，（S+Si）/O比。结果表明，大（12个数量级）的压力变化并不显着影响冷凝序列，虽然平衡序列的温度移动超过2的因素。描述了一个场景，试图解释观察到的氧，镁，氖，氙同位素异常。太阳前星云的四个组成部分被认为是：星际气体和尘埃（在整个银河系历史中被超新星富集）和“最后事件”的气体和尘埃，这些气体和尘埃是在陨石凝固之前大约10/sup 6/yr »发生的超新星产生的。这颗超新星可能是解释/sup 26/Mg异常所必需的。只有在太阳前星云的物理环境中稳定的矿物质才能存活下来。四个组件的情况下，可以解释从镁（10/sup 8/ yr）同位素测量推断从核合成到冷凝所经历的时间明显的差异。«少
Some of the observed isotopic anomalies in meteorites may be due to presolar grains that originated in supernova explosions. This hypothesis is investigated by performing chemical equilibrium condensation calculations with pressures and compositions that may be appropriate to cooling supernova ejecta. The presupernova star is assumed to have an ''onionskin'' appearance, the different layers being due to the successive static nuclear burning stages. During the supernova explosion each of these layers undergoes explosive nucleosynthesis. The resulting chemical and isotopic compositions of each layer are discussed. Chemical condensation calculations are then performed for each layer, for several different values of the total pressure, the C/O ratio, and, for the explosive oxygen-burning shell, the (S+Si)/O ratio. It is shown that large (twelve orders of magnitude) changes in the pressure do not significantly affect the condensation sequence, although the equilibrium sequence is shifted in temperature by more than a factor of 2. A scenario is described that attempts to explain the observed isotopic anomalies in oxygen, magnesium, neon, and xenon. Four components of the presolar nebula are considered: interstellar gas and dust (enriched by supernovae throughout galactic history) and ''last-event'' gas and dust produced by a supernova which occurred about 10/sup 6/ yrmore » before the meteorites solidified. This supernova may be necessary to explain the /sup 26/Mg anomaly. Only minerals that are stable in the physical environment of the presolar nebula can survive. The four-component scenario may account for the apparent discrepancy in the elapsed time from nucleosynthesis to condensation inferred from magnesium (10/sup 8/ yr) isotopic measurements.« less