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Early Planet Formation: A Facility to Study the Time Evolution and Equilibrium States of Multitudes of Interacting sub-millimeter to centimeter Dust and Ice Aggregate Ensembles

早期行星形成：研究大量相互作用的亚毫米到厘米尘埃和冰聚集体的时间演化和平衡状态的设施

基本信息

批准号：
237510420
负责人：
Professor Dr. Gerhard Wurm, since 3/2016
金额：
--
依托单位：
Forschungsgruppe Experimentalphysik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/237510420?language=en
关键词：
Early Planet Formation Facility Study

项目摘要

Planetary formation takes place in accretion disks (protoplanetary disks) around newly formed stars. The early phase is dominated by collisional growth of dust and ice aggregates: The initially micron sized dust and ice particles collide, stick together by surface forces and form larger aggregates which are the seeds for further growth. Up to millimeter size collisions are dominated by sticky interactions. However, the outcome of collision of sub-mm to mm/cm sized dust and ice aggregates is till this date unclear, even a emph(boucing barrier) is postulated for the typical collision velocities in a disk of mm/s to cm/s. This might prevent further growth (no more sticking) or might also be beneficial (sweep-up of the small aggregates by larger bodies). Hence, the intermediate stage of planet formation is not sufficiently understood.It was recently discovered that free collisions of sub-mm to several cm dust and ice aggregates within the mm/s to cm/s regime can be realized in the laboratory by levitating aggregates over a surface by a Knudsen compressor effect. Collisions between the levitating dust and ice aggregates with mm/s to cm/s are frequently (several per second) observable and probabilities for sticking, bouncing and fragmentation and their details can be gained over unlimited periods of time. Hence, the details of single collisions and espacially the time evolution towards equilibrium states of a system of multitudes of interacting dust or ice aggregates are experimental accessible.At the inner edge and at the optically thin parts of protoplanetary disks dust aggregates are irradiated by the host star. It was also just recently discovered that aggregates are subject to a photophoretic force which accelerates the dust. Having multitudes of free levitating aggregates in the laboratory, studies of photophoresis are possible.In this project we carry out collision experiments in the laboratory with and without the influence of photophoresis: The time evolution of thousands of free interacting sub-mm to cm dust and ice aggregates is easily accessible in the laboratory for the first time which will be studied in detail here.

行星的形成是在新形成的恒星周围的吸积盘(原行星盘)中进行的。早期阶段主要是尘埃和冰聚集体的碰撞生长：最初微米大小的尘埃和冰粒碰撞，在表面力的作用下粘在一起，形成更大的聚集体，这是进一步生长的种子。最大到毫米大小的碰撞主要是粘性相互作用。然而，亚毫米到毫米/厘米大小的尘埃和冰团的碰撞结果到目前为止还不清楚，甚至对于毫米/S到厘米/S的圆盘中典型的碰撞速度也假设了一个FEPH(束流势垒)。这可能会阻止进一步的增长(不再粘连)，也可能是有益的(较大天体对小集合体的扫掠)。最近发现，在毫米/S到厘米/S范围内，亚毫米级尘埃和冰团的自由碰撞可以通过克努森压缩效应将聚集体悬浮在表面上来实现。漂浮的尘埃和冰团聚体之间的碰撞(mm/S到cm/S)经常是可以观察到的(每秒几次)，粘连、反弹和碎裂的概率和它们的细节可以在无限的时间段内获得。因此，单个碰撞的细节，特别是大量相互作用的尘埃或冰聚集体系统向平衡态的时间演化是可以实验获得的。在原行星盘的内缘和光学薄的部分，尘埃聚集体受到主星的辐射。最近还发现，聚集体受到一种光生力量的影响，这种力量会加速尘埃的形成。由于实验室中有大量的自由悬浮集合体，光电泳性的研究是可能的。在这个项目中，我们在实验室中进行了在有无光电泳性影响的情况下的碰撞实验：数千个亚毫米到厘米级的自由相互作用的尘埃和冰聚集体的时间演化首次在实验室中很容易获得，这将在这里进行详细的研究。