论文标题
R-Process元素以银河系的动荡混合
Turbulent mixing of r-process elements in the Milky Way
论文作者
论文摘要
我们通过分析方法和蒙特卡洛模拟的结合，研究了$ r $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ r $的过程的湍流气体扩散的影响。较高的$ r $ - 过程事件速度和更快的扩散，导致更有效的混合，对应于$ r $ $ process的丰度减少，并导致$ r $ r $ - 过程富含的星星开始以较低的金属率开始出现。我们使用三个独立的观察来限制模型参数：（i）放射性稳定$ r $ - 过程元素丰度的散射，（ii）最大的$ r $ r $ - 程序丰富值在任何太阳能邻里明星中观察到的富集值，以及（iii）（iii）同位素丰度比例的不同放射性$ r $ -process elements（$ r $ -process）（$ r $ -process）（$^$^$^$^$^a 244） $^{247} $ cm/$^{238} $ u在早期太阳系与其编队相比。我们的结果表明，银河$ r $ - 过程和扩散系数分别为$ r <4 \ times 10^{ - 5} \ mbox {yr}^{ - 1}，d> 0.1 \ mbox { yr}^{-1}, D>0.5 \mbox{ kpc}^2\mbox{Gyr}^{-1}$ for collapsars or similarly prolific $r$-process sources) with allowed values satisfying an approximate anti-correlation such that $D\approx r^{-2/3}$, implying that the time between two $r$-process events that在银河系中丰富相同的位置，为$τ_ {\ rm mix} \大约100-200 \ mbox {myr} $。这表明，观察到的$^{247} $ cm（$^{244} $ pu）的$ \ sim 0.8 $ 0.8 $（$ \ sim 0.5 $）的丰度在早期太阳能系统中的一个$ r $ - 程序事件主导。放射性稳定的元素丰度以$ \ sim 10 $不同的太阳系中的不同事件为主。对于金属可怜的恒星（带有[Fe/h] $ \ Lessim -2 $），它们的$ r $ - 过程丰度由单个事件或几个事件主导，具体取决于星形的历史。
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 ($^{244}$Pu/$^{238}$U and $^{247}$Cm/$^{238}$U) 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 $r<4\times 10^{-5}\mbox{ yr}^{-1}, D>0.1 \mbox{ kpc}^2\mbox{Gyr}^{-1}$ ($r<4\times 10^{-6}\mbox{ yr}^{-1}, D>0.5 \mbox{ kpc}^2\mbox{Gyr}^{-1}$ for collapsars or similarly prolific $r$-process sources) with allowed values satisfying an approximate anti-correlation such that $D\approx r^{-2/3}$, implying that the time between two $r$-process events that enrich the same location in the Galaxy, is $τ_{\rm mix}\approx 100-200\mbox{ Myr}$. This suggests that a fraction of $\sim 0.8$ ($\sim 0.5$) of the observed $^{247}$Cm ($^{244}$Pu) abundance is dominated by one $r$-process event in the early solar system. Radioactively stable element abundances are dominated by contributions from $\sim 10$ different events in the early solar system. For metal poor stars (with [Fe/H]$\lesssim -2$), their $r$-process abundances are dominated by either a single or several events, depending on the star formation history.
