【摘要】 硅酸盐尘粒是宇宙尘埃的主要成分之一,它广泛存在于许多天体物理环境中,其特性随环境而变化。由于近年来观测数据的不断增加和红外光谱质量的逐步提高,宇宙空间中的硅酸盐尘粒正受到越来越多的关注．该文详细地介绍了在各种天体环境(星际空间、演化晚期恒星的星周尘埃包层、绕年轻恒星和主序星的星周尘埃盘、彗星的彗发和行星际空间)中的硅酸盐尘粒的观测特征,并分别对其物理和化学性质进行了综合比较．观测已经证实在星际尘埃演化的前身(演化晚期恒星的星周尘埃包层)和其遗迹(彗星)均有可观数量的结晶硅酸盐存在。但是至今还没有在其中间态(弥散星际介质)找到结晶硅酸盐存在的证据。这一尚未解决的难题突出了结晶态硅酸盐在天体物理研究中的重要意义。更多还原

【Abstract】 Silicate grains,one of the major cosmic dust species,are ubiquitously seen in various astronomical environments through their vibrational absorption or emission bands:Si-O stretch- ing at about 9.7μm and O-Si-O bending at about 18μm.Their physical and chemical properties vary with local environments,as revealed through the variations in the spectral shapes,relative intensities,and peak wavelengths of the silicate bands,both amorphous and crystalline.With the advent of both ground-based and space-borne infrared telescopes and the rapid accumulation of high-quality observational data,astronomical silicates have been receiving much attention in re- cent years,in this review,we summarize the observational characteristics of silicate grains in the interstellar medium,dust torus around Active Galactic Nuclei,protoplanetary dust disks around pre-main sequence stars,debris disks around main sequence stars,circumstellar envelopes around evolved stars,cometary coma,and interplanetary space.Their physical and chemical proper- ties in different astronomical regions are studied on a comparison basis,with special attention paid to crystalline silicates:whereas crystallinity is prevalent at the beginning(i.e.circumstel- lar envelopes around evolved stars)and end(i.e.cometary dust)of dust grains’ life cycle,no crystallinity is found in the intermediate phase(i.e.,in the diffuse interstellar medium).The as- trophysical implications of the presence and absence of crystalline silicates in certain astrophysical regions are discussed.更多还原