Abstract

The results of mathematical (simulation) modeling of the structure and properties of heterogeneous fractal dust–ice clusters ~0.1–10 cm in size and their disintegration into fragments at the water snow line in protoplanetary disks are presented. The main goal of this paper is to clarify the conditions under which the decay of such a cluster as a result of ice sublimation leads to the formation of large fragments comparable in mass and size with the initial cluster or, on the contrary, small and low-mass fragments. The predominance by mass of large or small fragments on the inner side of the snow line, taking into account the differences in their interaction with the gas in the disk, can have a significant effect on the localization and specificity of the formation of planetesimals. It is assumed that the clusters consist of dust aggregates of two types: one is predominantly of water ice with a small admixture of a more refractory material, the other is predominantly of a material less volatile than ice; at the same time, the sizes of aggregates of both types are tens to hundreds of times smaller than the size of the cluster. The ratios of sizes, densities and mass fractions of aggregates of both types are variable parameters. When choosing the values of these parameters, cometary data are used. We showed that large massive fragments on the inner side of the snow line can form if ice aggregates are, on average, much larger than refractory ones. In this case, massive refractory fragments are formed even at a relatively high mass fraction of water ice (≿0.3), consistent with the protosolar mass ratio of refractory and ice components ≤2, provided that the ratio of densities of refractory and ice aggregates is ≲3. If the density ratio is of the order of 10, then massive fragments are formed with a much lower ice fraction (~0.1), which, however, does not contradict cometary data.

中文翻译：

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模拟原行星盘雪线处尘埃-冰团的碎裂

摘要

介绍了对大小约 0.1-10 厘米的异质分形尘埃-冰团的结构和特性的数学（模拟）建模结果，以及它们在原行星盘中的水雪线处分解成碎片的结果。本文的主要目标是阐明在何种条件下，由于冰升华导致的此类星团衰变导致形成质量和大小与初始星团相当的大碎片，或者相反，小而低的碎片。 -大量碎片。考虑到它们与圆盘中气体相互作用的差异，雪线内侧的大碎片或小碎片的质量占优势，可以对星子形成的定位和特异性产生重大影响。假设集群由两种类型的尘埃聚集体组成：一种主要是水冰和少量更难熔材料的混合物，另一种主要是一种比冰挥发性低的材料；同时，两种类型的聚集体的大小都比簇的大小小几十到几百倍。两种类型的聚集体的尺寸、密度和质量分数的比率是可变参数。在选择这些参数的值时，将使用彗星数据。我们表明，如果冰聚集体平均比耐火材料大得多，则雪线内侧的大块碎片可以形成。在这种情况下，即使在相对较高质量分数的水冰（≿0.3）下，也会形成大量的耐火碎片，与原太阳质耐火组分与冰组分的质量比≤2一致，条件是耐火组分与冰聚集体的密度比≥3。如果密度比为 10 的数量级，则形成的大块碎片的冰分数要低得多（~0.1），但这与彗星数据并不矛盾。