微重力多粒子实验中的自由碰撞。II。尘埃包覆球粒的碰撞动力学
Free Collisions in a Microgravity Many-Particle Experiment. II. The Collision Dynamics of Dust-Coated Chondrules
摘要：
在早期太阳系中的微行星的形成很难被理解，特别是超过毫米大小的尘埃聚集体的生长最近被证明是我们理解的一项困难的任务[Zsom et al. 2010，A & A，513，A57]。实验室实验表明，这些大小的尘埃聚集体只有在不合理的低速度下才能相互粘附。然而，在原行星盘中，毫米大小的粒子是普遍存在的。人们可以找到它们的遗迹，以固体球粒的形式作为陨石的主要成分。大多数陨石球粒被发现具有细粒边缘，这被假设是由太阳星云中的吸积尘埃颗粒形成的。为了研究这些尘埃覆盖的球粒对陨石和可能的星子形成的影响，我们进行了毫米大小的尘埃覆盖的球粒类似物之间的碰撞实验，速度为几厘米/秒。对于2和3毫米直径的球粒类似物覆盖的灰尘边缘的体积填充因子为0.18和0.35 - 0.58，我们发现坚持几厘米/秒的速度。这一速度高于相同尺寸的粉尘聚集体的粘附速度。因此，我们得出结论，陨石球粒可能是一个重要的一步，更深入地了解碰撞增长的大型机构。此外，我们分析了碰撞行为的尘埃聚集体和非涂层球粒类似物的合奏。虽然尘埃聚集体和固体球粒类似物都没有在它们的物种之间的碰撞中显示出粘附，但我们发现两种成分之间的碰撞具有增强的sicking效率，这使我们推测球粒可能充当年轻太阳系中较大天体生长的"催化剂"。
英文摘要：
The formation of planetesimals in the early Solar System is hardly understood, and in particular the growth of dust aggregates above millimeter sizes has recently turned out to be a difficult task in our understanding [Zsom et al. 2010, A&A, 513, A57]. Laboratory experiments have shown that dust aggregates of these sizes stick to one another only at unreasonably low velocities. However, in the protoplanetary disk, millimeter-sized particles are known to have been ubiquitous. One can find relics of them in the form of solid chondrules as the main constituent of chondrites. Most of these chondrules were found to feature a fine-grained rim, which is hypothesized to have formed from accreting dust grains in the solar nebula. To study the influence of these dust-coated chondrules on the formation of chondrites and possibly planetesimals, we conducted collision experiments between millimeter-sized, dust-coated chondrule analogs at velocities of a few cm/s. For 2 and 3 mm diameter chondrule analogs covered by dusty rims of a volume filling factor of 0.18 and 0.35-0.58, we found sticking velocities of a few cm/s. This velocity is higher than the sticking velocity of dust aggregates of the same size. We therefore conclude that chondrules may be an important step towards a deeper understanding of the collisional growth of larger bodies. Moreover, we analyzed the collision behavior in an ensemble of dust aggregates and non-coated chondrule analogs. While neither the dust aggregates nor the solid chondrule analogs show sticking in collisions among their species, we found an enhanced sicking efficiency in collisions between the two constituents, which leads us to the conjecture that chondrules might act as "catalyzers" for the growth of larger bodies in the young Solar System.
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