The role of water in the process of planet formation

长期以来，人们一直推测水冰在行星形成过程中起着重要作用，特别是在尘埃聚集占主导地位的初始阶段。一种猜测是，圆盘中所谓的“冰线”附近的固体密度可能比其他地方要高得多，这导致了尘埃聚集的首选条件。另一种猜测是，有冰幔的粉尘颗粒比裸露的粉尘颗粒具有更好的粘附性能，甚至可能通过在“冰线”附近烧结的过程而增强。在早期的工作中，我们已经开发了一套复杂的数值工具，用于模拟太阳系最初几兆年内随时间变化的尘埃凝聚和运输。该模型的输入物理是基于实验室实验的。如果粉尘颗粒是裸露的硅酸盐颗粒，则粉尘聚集倾向于在1mm大小的团聚体中停止。在这个提议中，我们希望找出水冰是否可以帮助克服这种增长的停滞，以及对原始太阳星云中水的存在和运输的各种太阳系限制的预测是什么。

It has been long speculated that water ice plays an important role in the process of planet formation, in particular the initial phase in which dust aggregation dominates. One suspicion is that the density of solids near the so-called “ice line” in the disk may have been much higher than elsewhere, leading to preferred conditions for dust aggregation. Another suspicion is that dust grains with ice mantels have better sticking properties than bare dust grains, possibly even enhanced by the process of sintering near the “ice line”. In earlier work we have developed a sophisticated numerical tool set for modeling time-dependent dust coagulation and transport in the first few Megayear of the solar system. The input physics of this model is based on laboratory experiments. It was found that dust aggregation tends to halt at 1 mm size aggregates, if the dust particles are bare silicate grains. In this proposal we wish to find out if water ice can help overcome this stalling of the growth, and what the predictions are for various solar system constraints on the presence and transport of water in the primitive solar nebula.