Thermal annealing of silicates in protoplanetary disks - Laboratory data and modelling

本项目旨在获得硅酸盐矿物热退火过程中发生的物理化学过程的可靠实验室数据。这些数据是建立一致的天体物理模型所迫切需要的。结晶度对原行星盘的不透明度、辐射传递和热结构具有至关重要的影响。通过对原行星盘和彗星的红外光谱观察到各种各样的矿物，特别是在宇宙化学上丰富的富含镁的橄榄石和辉石群硅酸盐。在这个项目中，这些硅酸盐的热退火将在实验室通过加热的非晶材料的红外光谱进行跟踪。红外结果将与其他方法（如x射线衍射和透射电子显微镜）的结果相关联，以更好地定义结晶度作为时间和退火温度的函数。数值技术和从头计算将用于模拟结晶过程和模拟红外光谱在此过程中的演变。

This project aims at obtaining reliable laboratory data on the physico-chemical processes taking place during thermal annealing of silicate minerals. These data are urgently needed for a consistent astrophysical modelling. The degree of crystallinity is of utmost importance for the opacity, radiative transfer and thermal structure of protoplanetary disks. A variety of minerals - particularly the cosmochemically abundant Mg-rich silicates of the olivine and pyroxene groups - have been observed via infrared spectroscopy of protoplanetary disks and comets. In this project, thermal annealing of these silicates will be traced in the laboratory by infrared spectroscopy of heated amorphous materials. The infrared results will be correlated with those of other methods (e.g. X-ray diffractometry and transmission electron microscopy) to better define the degree of crystallinity as a function of time and annealing temperature. Numerical techniques and ab initio calculations will be used to model the crystallisation process and simulate the evolution of infrared spectra during this process.