Synthesis of actinides and short-lived radionuclides during i-process nucleosynthesis in AGB stars

IF 2.6 3区 物理与天体物理 Q2 PHYSICS, NUCLEAR
Arthur Choplin, Stephane Goriely, Lionel Siess, Sébastien Martinet
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引用次数: 0

Abstract

A complex interplay between mixing and nucleosynthesis is at work in asymptotic giant branch (AGB) stars. In addition to the slow neutron capture process (s-process), the intermediate neutron capture process (i-process) can develop during proton ingestion events (PIEs). In this paper, after quickly reviewing the different modes of production of heavy elements in AGB stars that have been identified so far, we investigate the synthesis of actinides and other short-lived radioactive nuclei (SLRs, \(^{60}\)Fe, \(^{107}\)Pd, \(^{126}\)Sn, \(^{129}\)I, \(^{135}\)Cs, and \(^{182}\)Hf) during i-process nucleosynthesis. AGB stellar models with initial masses \(1 \le M_\textrm{ini}/M_{\odot }\le 3\), metallicities \(-3 \le \) [Fe/H] \( \le 0\), and different overshoot strengths were computed with the stellar evolution code STAREVOL. During PIEs, a nuclear network of 1160 isotopes is used and coupled to the transport equations. We found that AGB models with [Fe/H] \(<-2\) can synthesize actinides with abundances sometimes greater than solar values. The \(^{60}\)Fe yield scales with the initial metallicity, while the \(^{107}\)Pd, \(^{126}\)Sn, \(^{129}\)I, \(^{135}\)Cs, and \(^{182}\)Hf yields follow a similar pattern as a function of metallicity, with a production peak at [Fe/H] \(\simeq -1.3\). At [Fe/H] \(<-1\), the fraction of odd Ba isotopes \(f_\textrm{Ba,odd}\) is predicted to vary between 0.6 and 0.8 depending on the initial mass and metallicity. Nuclear uncertainties on our 1\(~M_{\odot }\)  [Fe/H] \(=-2.5\) model lead to \(f_\textrm{Ba,odd}\) ranging between 0.27 and 0.76, which is clearly above the s-process value. AGB stars experiencing PIEs appear to be potential producers of actinides and SLRs, particularly at low metallicity (except for \(^{60}\)Fe). Galactic chemical evolution modelling is required to assess their possible contribution to the galactic enrichment.

AGB星核合成过程中锕系元素和短寿命放射性核素的合成
在渐近巨支(AGB)恒星中,混合和核合成之间存在着复杂的相互作用。除了慢中子捕获过程(s过程),中间中子捕获过程(i过程)可以在质子摄取事件(pie)中发生。在本文中,在快速回顾了迄今为止已经确定的AGB恒星中重元素的不同生产模式之后,我们研究了在I过程核合成过程中锕系元素和其他短寿命放射性原子核(SLRs, \(^{60}\) Fe, \(^{107}\) Pd, \(^{126}\) Sn, \(^{129}\) I, \(^{135}\) Cs和\(^{182}\) Hf)的合成。用恒星演化程序STAREVOL计算了初始质量\(1 \le M_\textrm{ini}/M_{\odot }\le 3\)、金属丰度\(-3 \le \) [Fe/H] \( \le 0\)和不同超调强度的AGB恒星模型。在pie过程中,使用了1160个同位素的核网络,并将其耦合到输运方程中。我们发现含有[Fe/H] \(<-2\)的AGB模型可以合成丰度有时大于太阳值的锕系元素。\(^{60}\) Fe产率随初始金属丰度变化,而\(^{107}\) Pd、\(^{126}\) Sn、\(^{129}\) I、\(^{135}\) Cs和\(^{182}\) Hf产率随初始金属丰度变化规律相似,产率峰值为[Fe/H] \(\simeq -1.3\)。在[Fe/H] \(<-1\),根据初始质量和金属丰度的不同,预计Ba同位素奇数的比例\(f_\textrm{Ba,odd}\)在0.6和0.8之间变化。我们的1 \(~M_{\odot }\) [Fe/H] \(=-2.5\)模型的核不确定性导致\(f_\textrm{Ba,odd}\)的范围在0.27和0.76之间,这明显高于s过程值。经历pie的AGB恒星似乎是锕系元素和单反的潜在生产者,特别是在金属丰度低的情况下(\(^{60}\) Fe除外)。需要建立星系化学演化模型来评估它们对星系富集的可能贡献。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
The European Physical Journal A
The European Physical Journal A 物理-物理:核物理
CiteScore
5.00
自引率
18.50%
发文量
216
审稿时长
3-8 weeks
期刊介绍: Hadron Physics Hadron Structure Hadron Spectroscopy Hadronic and Electroweak Interactions of Hadrons Nonperturbative Approaches to QCD Phenomenological Approaches to Hadron Physics Nuclear and Quark Matter Heavy-Ion Collisions Phase Diagram of the Strong Interaction Hard Probes Quark-Gluon Plasma and Hadronic Matter Relativistic Transport and Hydrodynamics Compact Stars Nuclear Physics Nuclear Structure and Reactions Few-Body Systems Radioactive Beams Electroweak Interactions Nuclear Astrophysics Article Categories Letters (Open Access) Regular Articles New Tools and Techniques Reviews.
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