Laboratory measurements of the far-infrared to millimeter dust opacity at low temperatures

冷尘埃远红外线至毫米波段的热发射是研究星际介质空间分布的重要信息来源。赫歇尔、普朗克和ALMA在这个光谱范围内的观测结果的解释，取决于对尘埃粒子发射特性的确切了解，即尘埃的不透明度。然而，现有的不透明度数据仅基于对某些选定材料的相对较少的实验室测量，并且对潜在的物理效应的理解仍然很差。虽然温度对亚毫米不透明度的强烈影响在原则上是已知的，但到目前为止，在低温下只进行了几次测量。该项目的目的是通过实验室测量重要的星际尘埃材料，如不同铁含量的无定形硅酸盐（第一阶段）、碳质材料（第二阶段）以及硅酸盐、冰和碳基或铁基材料的混合物，来扩大这个数据库。研究了温度、非均匀成分和颗粒团聚对不透明度的影响。了解物理相互关系和改进天体物理尘埃模型需要在宽波长范围内进行测量，我们通过结合两个研究所（耶拿和科隆）的经验和设备来实现这一目标。

The thermal emission of cold dust in the far infrared up to the millimeter range is an important source of information for studies of the spatial distribution of the interstellar medium. The interpretation of observations in this spectral range, as they were or are performed with Herschel, Planck, and ALMA, depends on the exact knowledge of the emission properties of the dust particles, i.e. the dust opacity. The available opacity data, however, are based on relatively few laboratory measurements for some selected materials only and on a still quite poor understanding of the underlying physical effects. Although the strong influence of temperature on the sub-millimeter opacity is known in principle, so far only a few measurements at low temperatures have been carried out. The aim of the project is to broaden this data base by laboratory measurements on important interstellar-dust materials such as amorphous silicates of different iron content (phase I), carbonaceous materials (phase II), and for mixtures e.g. of silicate, ice and carbon- or iron-based materials. The influence of temperature, of inhomogeneous compositions and of particle agglomeration on the opacity will be investigated in detail. Understanding the physical interrelations and improving the astrophysical dust models requires measurements in a wide wavelength range, which we achieve by combining experiences and devices from two institutes (Jena and Cologne).