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arXiv 1909.06361astro-ph.EP
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放射性核素相对丰度对太阳系形成环境的制约

The birth environment of the solar system constrained by the relative abundances of the solar radionuclides

Edward Young

备注：
9 pages, 2 figures, in press, IAU, Cambridge University Press. arXiv admin note: substantial text overlap with arXiv:1605.07096
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摘要：

放射性核素在太阳系诞生时的相对丰度是关于太阳诞生环境的相互竞争的假设的关键仲裁者。短寿命放射性核素的存在，如陨石中的衰变产物所证明的，被用来表明特定的，有时是外来的恒星源接近太阳的诞生环境。最近确认的中子星-中子星（NS-NS）合并和相关的kilonovae作为潜在的主要来源的r-过程核素可以测试的情况下，太阳诞生的环境中使用的相对丰度的较长寿命的核素。对15种放射性核素及其稳定的伙伴（其丰度和生产率是众所周知的）的批判性分析表明，太阳形成于一个典型的大质量恒星形成区（SFR）。短寿命放射性核素的表观过量（例如，早期太阳系的$^{26} {\rm Al}$、$^{41}{\rm Ca}$、$^{36}{\rm Cl}$）似乎是迄今为止对沃尔夫-拉叶风在SFR中富集的重要影响认识不足的人为产物。长寿命核素（例如，$^{238}{\rm U}$、$^{244}{\rm Pu}$、$^{247}{\rm Cr}$、$^{129}{\rm I}$）与生产事件之间的平均时间间隔$10^8$年一致，似乎太短，不可能是单独的NS-NS合并的产物。所有这些核素的相对丰度可以用它们的平均衰变寿命和在$\sim200$ Myr ISM中的平均停留时间来解释。放射性核素所证明的这种停留时间与ISM中尘埃的平均寿命和将分子云质量转换为恒星的时间尺度一致。

英文摘要：

The relative abundances of the radionuclides in the solar system at the time of its birth are crucial arbiters for competing hypotheses regarding the birth environment of the Sun. The presence of short-lived radionuclides, as evidenced by their decay products in meteorites, has been used to suggest that particular, sometimes exotic, stellar sources were proximal to the Sun's birth environment. The recent confirmation of neutron star - neutron star (NS-NS) mergers and associated kilonovae as potentially dominant sources of r-process nuclides can be tested in the case of the solar birth environment using the relative abundances of the longer-lived nuclides. Critical analysis of the 15 radionuclides and their stable partners for which abundances and production ratios are well known suggests that the Sun formed in a typical massive star-forming region (SFR). The apparent overabundances of short-lived radionuclides (e.g.\, $^{26} {\rm Al}$, $^{41}{\rm Ca}$, $^{36}{\rm Cl}$) in the early solar system appears to be an artifact of a heretofore under-appreciation for the important influences of enrichment by Wolf-Rayet winds in SFRs. The long-lived nuclides (e.g.\, $^{238}{\rm U}$, $^{244}{\rm Pu}$, $^{247}{\rm Cr}$, $^{129}{\rm I}$) are consistent with an average time interval between production events of $10^8$ years, seemingly too short to be the products of NS-NS mergers alone. The relative abundances of all of these nuclides can be explained by their mean decay lifetimes and an average residence time in the ISM of $\sim200$ Myr. This residence time evidenced by the radionuclides is consistent with the average lifetime of dust in the ISM and the timescale for converting molecular cloud mass to stars.

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