Dust Processing during the Gravitational Collapse of Particle Heaps

颗粒堆重力塌陷过程中的粉尘处理

• 批准号: 158706757
• 负责人: Professor Dr. H. Hubertus Klahr
• 金额: --
• 依托单位: Max-Planck-Institut für Astronomie (MPIA)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/158706757?language=en
• 关键词: Dust; Processing; during; Gravitational; Collapse

In this project we will investigate the fate of the material which is building up planetesimals during the gravitational collapse of heaps of planetesimal precursors (0.1cm - 1m). A very attractive way to form the kilometre sized Planetesimals in the early solar system is the ”Gravoturbulent Fragmentation” of a cloud of relatively small icy and dusty objects. In a nonturbulent e.g. laminar disk sedimentation of particles leads rather to a Kelvin-Helmholtz instability driven turbulence than to a particle layer dense enough for gravitational collapse (Goldreich-Ward instability). Latest studies on the coagulation efficiency of dust aggregates have shown that cm-sized dust aggregates can rapidly form. However, any further growth seems to be inhibited by either the bouncing or the fragmentation barrier. Hence, Johansen et al. (2006a, 2007) came up with a hybrid scenario in which turbulent concentration of depending on the location in the disk millimetre to meter sized icy and dusty material leads to sufficiently large densities in which self gravity dominates over gas drag and the tidal forces of the star, thus a heap of material collapses spontaneously under its own weight into a many kilometre sized planetesimal. In the proposed project we aim to investigate the effect of the collisions during the gravitational fragmentation3 phase. A main question we want to address here, is whether a collisional fragmentation of the solids could stop the collapse and thus diminish or destroy the possibility to form planetesimals from gravitational fragmentation.

在这个项目中，我们将调查的命运的材料，这是建立在引力坍缩的星子堆的星子前体（0.1厘米-1米）。在早期太阳系中，形成千米大小的星子的一个非常有吸引力的方法是由相对较小的冰冷和尘埃物体组成的云的“重力湍流破碎”。在非湍流的情况下，例如在层流盘中，粒子的沉降会导致开尔文-亥姆霍兹不稳定性驱动的湍流，而不是导致粒子层密度足以引起引力坍缩（戈德里希-沃德不稳定性）。对粉尘凝聚体凝聚效率的最新研究表明，厘米级粉尘凝聚体可以迅速形成。然而，任何进一步的增长似乎都受到反弹或碎片障碍的抑制。因此，Johansen等人（2006 a，2007）提出了一种混合方案，其中取决于盘中毫米到米大小的冰和尘埃物质的湍流浓度导致足够大的密度，其中自引力超过气体阻力和星星的潮汐力，因此一堆物质在其自身重量下自发地坍塌成许多公里大小的微行星。在拟议的项目中，我们的目标是调查在引力碎裂3阶段碰撞的影响。我们在这里要解决的一个主要问题是，固体的碰撞碎裂是否可以阻止坍缩，从而减少或破坏引力碎裂形成微行星的可能性。