论文标题
通过湍流聚类形成行星形成的级联模型
Cascade Model for Planetesimal Formation by Turbulent Clustering
论文作者
论文摘要
我们使用新开发的原星云中颗粒湍流浓度的级联模型来计算产生原始行星和陨石记录的几种感兴趣的特性。该模型遵循Cuzzi等人对主要行星初始质量函数（IMF）的计算。 （2010年），其中使用了错误的级联模型。在这里，我们使用Hartlep等人的模型。 （2017年），已针对湍流中粒子浓度的几个已发表的数值模拟进行了验证。我们发现，对于一系列的星云和粒子特性，行星可能是“天生的”，形成的是直径在10-100 km范围内的沙留，直接从自由漂浮的颗粒中形成。 IMF具有模态性质，具有明确的峰值而不是PowerLaw尺寸依赖性。在这些方面，对内部和外部星云的预测也相似，并且对内和外部星云原始体的观察支持这种模态IMF。同样，我们在几个长度尺度上提出了局部颗粒浓度的预测，其中颗粒“通常”发现了自己，这对于在软骨形成区域的氧化还原态和同位素分馏的气象观察具有重要意义。这些结果与Cuzzi等人的结果之间的重要区别。 （2010年），是，必须最适合地满足IMF和气象性能至少达到至少1 few CM半径范围。也就是说，就内部星云而言，主要的“颗粒”必须是软骨（或软骨大小的前体）的聚集体，而不是单个的软骨本身。
We use a newly developed cascade model of turbulent concentration of particles in protoplanetary nebulae to calculate several properties of interest to the formation of primitive planetesimals and to the meteorite record. The model follows, and corrects, calculations of the primary planetesimal Initial Mass Function (IMF) by Cuzzi et al. (2010), in which an incorrect cascade model was used. Here we use the model of Hartlep et al. (2017), which has been validated against several published numerical simulations of particle concentration in turbulence. We find that, for a range of nebula and particle properties, planetesimals may be "born big", formed as sandpiles with diameters in the 10-100 km range, directly from freely floating particles. The IMFs have a modal nature, with a well-defined peak rather than a powerlaw size dependence. Predictions for the inner and outer nebula behave similarly in these regards, and observations of inner and outer nebula primitive bodies support such modal IMFs. Also, we present predictions of local particle concentrations on several lengthscales in which particles "commonly" find themselves, which have significance for meteoritical observations of the redox state and isotopic fractionation in regions of chondrule formation. An important difference between these results, and those of Cuzzi et al. (2010), is that particle growth-by-sticking must proceed to at least the 1-few cm radius range for the IMF and meteoritical properties to be most plausibly satisfied. That is, as far as the inner nebula goes, the predominant "particles" must be aggregates of chondrules (or chondrule-size precursors) rather than individual chondrules themselves.
