Planetesimal Formation at High Temperatures

行星形成的早期阶段很大程度上取决于尘埃颗粒的物质特性。特别是径向向内漂移和高温对原行星盘温暖内部的聚集有很大的影响。首先，实验室实验表明，在星子形成的早期阶段，高温确实可以极大地改变尘埃颗粒的粘附能力。该项目将系统地研究这一点，模拟从较冷到较高温度的南极和模型矿物样品的演变。将制作、加热原行星模拟样品，并通过X射线衍射、穆斯堡尔光谱、光学成像、电子显微镜方法和粒度分析对其组成进行分析。这些样品将在拉伸强度和碰撞实验中研究静态和动态粘附性能。最终的目标是发展一种关于局部微行星形成效率的想法。特别是，考虑到太阳系外行星的数量和变化在靠近其主星的温暖内部，这是一种理解行星形成的方法，迄今为止很少有人考虑。

Early phases of planet formation strongly depend of the material properties of the particles present as dust. Especially radial inward drift and high temperatures have a strong influence on the aggregation in the warm, inner parts of protoplanetary disks. First laboratory experiments show that during early phases of planetesimal formation high temperatures indeed can alter the sticking capabilities of dust grains tremendously. This project will study this in a systematic way as the evolution of chondritic as well as model mineral samples from cooler to higher temperatures will be simulated. Protoplanetary analog samples will be produced, heated and their composition will be analyzed by X-ray diffraction, Mössbauer spectroscopy, optical imaging, electronmicroscopical methods and particle size analysis. These samples will be studied cool and warm for static and dynamical sticking properties in tensile strength and collision experiments. Ultimate goal is to develop an idea on the efficiency of local planetesimal formation. Especially, in view of the large number and variation of extrasolar planets within the warm inner parts close to their host stars this is an approach for understanding planet formation that found little consideration so far.