A simple model for the evolution of the dust population in protoplanetary disks
A simple model for the evolution of the dust population in protoplanetary disks
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DOI：
10.1051/0004-6361/201118136
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发表时间：
2012-03-01
影响因子：
6.5
通讯作者：
Ercolano, B.
中科院分区：
文献类型：
--
作者：
Birnstiel, T.;Klahr, H.;Ercolano, B.
上下文尘埃的全球大小和空间分布是原行星盘的结构和演化以及更大天体（如微行星）形成的重要因素。我们的目标是推导出简单的方程，解释全球的尘埃表面密度分布的演变和粒度分布的上限，可以很容易地用于进一步建模或解释观测数据。我们已经开发了一个简单的模型，遵循的尘埃粒度分布的上端和尘埃表面密度分布的演变。该模型是校准与国家的最先进的模拟尘埃演变，治疗尘埃的增长，破碎，并在粘性发展的气体disk.Results.Results.我们发现非常好的协议之间的完整的灰尘演变代码和本文提出的玩具模型。我们推导出的分析配置文件，描述的尘埃-气体的比例和尘埃表面密度分布以及在原行星盘，以及径向通量的固体材料“雨”，这是至关重要的触发任何引力辅助形成的星子。我们发现，碎片化是在磁盘的内部区域的主导作用，导致尘埃表面密度指数为-1.5，而在以后的时间外部区域可以成为漂移为主，产生尘埃表面密度指数为-0.75。我们的研究结果表明，径向漂移是没有效率的破碎尘埃颗粒。这支持了这样一种理论，即小的尘埃颗粒是由于盘的湍流状态而被碎片化补充的。
Context. The global size and spatial distribution of dust is an important ingredient in the structure and evolution of protoplanetary disks and in the formation of larger bodies, such as planetesimals.Aims. We aim to derive simple equations that explain the global evolution of the dust surface density profile and the upper limit of the grain size distribution and which can readily be used for further modeling or for interpreting of observational data.Methods. We have developed a simple model that follows the upper end of the dust size distribution and the evolution of the dust surface density profile. This model is calibrated with state-of-the-art simulations of dust evolution, which treat dust growth, fragmentation, and transport in viscously evolving gas disks.Results. We find very good agreement between the full dust-evolution code and the toy model presented in this paper. We derive analytical profiles that describe the dust-to-gas ratios and the dust surface density profiles well in protoplanetary disks, as well as the radial flux by solid material "rain out", which is crucial for triggering any gravity assisted formation of planetesimals. We show that fragmentation is the dominating effect in the inner regions of the disk leading to a dust surface density exponent of -1.5, while the outer regions at later times can become drift-dominated, yielding a dust surface density exponent of -0.75. Our results show that radial drift is not efficient in fragmenting dust grains. This supports the theory that small dust grains are resupplied by fragmentation due to the turbulent state of the disk.