Turbulent mixing of r-process elements in the Milky Way
Turbulent mixing of r-process elements in the Milky Way
复制标题
银河系中 r 过程元素的湍流混合
DOI：
--
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发表时间：
2020
影响因子：
4.8
通讯作者：
K. Hotokezaka
中科院分区：
文献类型：
--
作者：
P. Beniamini;K. Hotokezaka
采用解析方法和蒙特卡罗模拟相结合的方法，研究了湍流气体扩散对银河系恒星r过程丰度的影响。更高的r过程事故率和更快的扩散导致更有效的混合，相应地减少了r过程丰度的分散，并导致r过程丰富的恒星开始出现在较低的金属丰度处。我们使用三个独立的观测来约束模型参数：(I)放射性稳定的r过程元素丰度的散布，(Ii)在任何太阳邻近恒星中观察到的最大r过程富集值，以及(Iii)不同放射性r过程元素(244Pu/238U和247Cm/238U)在太阳系早期的同位素丰度比。我们的结果表明，银河系的r过程速率和扩散系数分别是r<；4×10−5 yr−1，D>；0.1 kpc； Gyr−1(r<；4×10−6 yr−1，D>；0.5 kpc； Gyr−1，对于崩塌或类似多产的过程源)，它们的允许值满足近似的反关系，即D和≈r−2/3，意味着两个富含银河系同一位置的r过程事件之间的时间是τMix和≈100−200 Myr。这表明，在太阳系早期观测到的247Cm(244Pu)丰度中，∼0.8%(∼0.5%)是由一次r过程事件主导的。放射性稳定元素丰度主要由太阳系早期∼10个不同事件的贡献所决定。对于贫金属星(具有[Fe/H]和≲−2)，它们的r过程丰度由单个或多个事件主导，这取决于恒星形成的历史。
We study turbulent gas diffusion affects on r-process abundances in Milky Way stars, by a combination of an analytical approach and a Monte Carlo simulation. Higher r-process event rates and faster diffusion, lead to more efficient mixing corresponding to a reduced scatter of r-process abundances and causing r-process enriched stars to start appearing at lower metallicities. We use three independent observations to constrain the model parameters: (i) the scatter of radioactively stable r-process element abundances, (ii) the largest r-process enrichment values observed in any solar neighborhood stars, and (iii) the isotope abundance ratios of different radioactive r-process elements (244Pu/238U and 247Cm/238U) at the early Solar system as compared to their formation. Our results indicate that the Galactic r-process rate and the diffusion coefficient are respectively r < 4 × 10−5 yr−1, D > 0.1 kpc2 Gyr−1 (r < 4 × 10−6 yr−1, D > 0.5 kpc2 Gyr−1 for collapsars or similarly prolific r-process sources) with allowed values satisfying an approximate anticorrelation such that D ≈ r−2/3, implying that the time between two r-process events that enrich the same location in the Galaxy, is τmix ≈ 100−200 Myr. This suggests that a fraction of ∼0.8 (∼0.5) of the observed 247Cm (244Pu) abundance is dominated by one r-process event in the early Solar system. Radioactively stable element abundances are dominated by contributions from ∼10 different events in the early Solar system. For metal poor stars (with [Fe/H] ≲ −2), their r-process abundances are dominated by either a single or several events, depending on the star formation history.
DOI：
10.1111/j.1365-2966.2012.21859.x
发表时间：
2012-11-01
影响因子：
4.8
作者：
Korobkin, O.;Rosswog, S.;Winteler, C.
通讯作者：
Winteler, C.