Galactic Chemical Evolution of Radioactive Isotopes
Galactic Chemical Evolution of Radioactive Isotopes
复制标题
放射性同位素的银河化学演化
DOI：
10.3847/1538-4357/ab21d1
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
B. Gibson
中科院分区：
文献类型：
--
作者：
B. Cot'e;M. Lugaro;R. Reifarth;M. Pignatari;Blanka Világos;A. Yagüe;B. Gibson
在陨石包裹体形成时，其中存在短寿命的放射性同位素，这为研究导致太阳系形成的环境提供了一个独特的机会。为了解释这些观测结果，我们需要计算银河系中放射性同位素与稳定同位素比率的演变。我们提出了开源银河系化学演化代码NuPyCEE和JINAPyCEE的扩展，可以跟踪星际介质中放射性同位素的衰变。我们展示了同位素比的演化如何依赖于星星的形成历史和效率，恒星与气体的质量比，以及星系的外流。考虑到用于校准我们模型的观测结果的不确定性，我们对太阳形成时同位素比率的预测不确定性为3.6倍。此时，为了恢复由我们的模型预测的实际放射性同位素与稳定同位素的比率，可以将稳态解（参见等式（））乘以。然而，在放射性同位素的半衰期超过1.2亿年，或目标放射性或稳定同位素具有质量和/或金属性依赖的生产率，或它们来自具有不同延迟时间分布的不同来源，或参考同位素具有放射性的情况下，我们的代码应用于更准确的解决方案。我们的初步计算证实了早期太阳系中放射性核与r-和s-过程起源之间的二分法，55 Mn和60 Fe可以用银河系化学演化来解释，而26 Al不能。
The presence of short-lived (∼Myr) radioactive isotopes in meteoritic inclusions at the time of their formation represents a unique opportunity to study the circumstances that led to the formation of the solar system. To interpret these observations, we need to calculate the evolution of radioactive-to-stable isotopic ratios in the Galaxy. We present an extension of the open-source galactic chemical evolution codes NuPyCEE and JINAPyCEE that enable the decay of radioactive isotopes in the interstellar medium to be tracked. We show how the evolution of the isotopic ratio depends on the star formation history and efficiency, star-to-gas mass ratio, and galactic outflows. Given the uncertainties in the observations used to calibrate our model, our predictions for isotopic ratios at the time of formation of the Sun are uncertain by a factor of 3.6. At that time, to recover the actual radioactive-to-stable isotopic ratios predicted by our model, one can multiply the steady-state solution (see Equation ()) by . However, in the cases where the radioactive isotope has a half-life longer than ∼200 Myr, or the target radioactive or stable isotopes have mass- and/or metallicity-dependent production rates, or they originate from different sources with different delay-time distributions, or the reference isotope is radioactive, our codes should be used for more accurate solutions. Our preliminary calculations confirm the dichotomy between radioactive nuclei in the early solar system with r- and s-process origin, and that 55Mn and 60Fe can be explained by galactic chemical evolution, while 26Al cannot.
影响因子：
4.8
作者：
C. Brook;G. Stinson;Bradley K Gibson;Bradley K Gibson;S. Shen;A. Macciò;A. Obreja;J. Wadsley;Thomas P. Quinn
通讯作者：
C. Brook;G. Stinson;Bradley K Gibson;Bradley K Gibson;S. Shen;A. Macciò;A. Obreja;J. Wadsley;Thomas P. Quinn