Evolution of decimeter bodies - The missing link in planetesimal formation

分米天体的演化——星子形成中缺失的一环

• 批准号: 211385425
• 负责人: Dr. Jens Teiser
• 金额: --
• 依托单位: Forschungsgruppe Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/211385425?language=en
• 关键词: Evolution; decimeter; bodies; missing; link

Planets form by accretion of km-size protoplanetary bodies, so-called planetesimals, which grow from dust particles. Depending on the model, coagulation of dust agglomerates directly leads to km-sized bodies or planetesimals form by gravitational clumping of solids within protoplanetary disks. For both scenarios decimeter size bodies play a crucial role for the evolution of solid particles in protoplanetary disks. They are the direct precursors of meter-sized bodies, so it is crucial to understand the collision dynamics and the properties of decimeter size dust agglomerates. The threshold conditions for partial and/or total fragmentation are crucial parameters for coagulation models, as the particle size distributions strongly influence the evolution of protoplanetary disks. Current models on growth via gravitational instabilities are based on the assumption that all solid material within protoplanetary disks is already captured within decimeter sized bodies. The understanding of the dynamics of collisions between decimeter bodies at impact velocities of about 10 m/s is therefore crucial for gravitation driven growth of planetesimals. Despite of their importance, no data for collisions between dust agglomerates in this size range, neither theoretical nor experimental, exist so far. Within the proposed work collision experiments with decimeter sized dust agglomerates will be carried out. The threshold velocities for fragmentation will be determined in low velocity experiments. Additionally, the collision dynamics for high velocities (> 10 m/s) and the fragment distribution will be studied. The results will add crucial input for coagulation models and also for models describing gravitation driven growth.

行星的形成是由千米大小的原行星体，即所谓的行星体，由尘埃颗粒生长而成。根据模型的不同，尘埃凝聚体的凝聚直接导致千米大小的天体或行星体的形成，这是通过原行星盘内固体的重力聚集而形成的。在这两种情况下，分米大小的天体对原行星盘中固体粒子的演化都起着至关重要的作用。它们是米级天体的直接前兆，因此了解碰撞动力学和分米级尘埃凝聚体的性质是至关重要的。部分和/或全部破碎的阈值条件是凝聚模型的关键参数，因为颗粒尺寸分布强烈地影响着原行星盘的演化。目前关于引力不稳定性增长的模型是基于这样的假设，即原行星盘内的所有固体物质都已经被分米大小的天体捕获。因此，理解分米体在大约10m/S撞击速度下的碰撞动力学对于引力驱动的行星体生长是至关重要的。尽管它们很重要，但到目前为止，无论是理论上还是实验上，都没有关于这种大小范围内的尘埃聚集体之间碰撞的数据。在拟议的工作范围内，将进行与分米级尘埃凝聚体的碰撞实验。破碎的门槛速度将在低速实验中确定。此外，还将研究高速(&gt；10m/S)的碰撞动力学和碎片分布。这一结果将为凝聚模型和描述引力驱动增长的模型增加关键的输入。