The measurements of optical properties of candidate materials for circumstellar and interstellar dust in far-infrared region and application to infrared astronomy

自天文台红外空间观测以来，在年轻天体和演化天体的星周中到处都发现了晶体硅酸盐。这些事实与无定形尘埃的传统观念相矛盾。为了弄清尘埃物质的演变和尘埃的质量，需要各种材料光学性质的良好数据。但是，只有很少的数据可以公布。结晶硅酸盐为富镁硅酸盐，如辉石mg2sio_4和顽辉石MgSiO_3。将橄榄石和辉石粒子冷却到液氦温度时，峰的位置移到更短的波长，峰变得更尖锐。这与观测结果一致，光谱显示了尖锐的峰和星周尘埃在低温下存在几个10 K。在宇宙中，镁元素和铁元素等量存在。因此，研究光谱随镁铁比的变化规律具有重要意义。通过对橄榄石和辉石红外光谱的测量，发现其红外光谱与Mg/Fe比值有关，且随着Mg含量的降低，峰值位置向较长波方向偏移。特别是，端元对Mg/Fe比非常敏感，峰移随Mg/Fe比的变化而急剧变化。我们通过观测到的65 μm宽波段和实验室测量数据，在演化天体周围探测到透辉石。这一宽波段被认为是由水冰产生的，但水冰在62 μm左右出现峰值，即使冷却到不同的温度。自从我们发现透辉石以来，许多工人都注意到高低温缩聚矿物，有的组还发现了方解石、白云石等碳酸盐矿物。近年来，根据缩合理论发现了许多新的矿物，对观测带的识别和物质的演化都非常有趣。

Since the observation of ISO (Infrared Space of Observatory), crystalline silicates were detected every where in circumstellar of young objects and evolved objects. These facts are contradicts against the traditional idea of amorphous dust. In order to make clear the evolution of dust material and mass quantity of dust, the good data of optical properties of various materials are needed. But, only few data can be published. Crystalline silicates are Mg-rich such as forsterite Mg_2SiO_4 and enstatite MgSiO_3. Cooling olivine and pyroxene particles to liquid helium temperature the peak positions are shifted to shorter wavelength and peaks become sharper. This is the same results of observation, which the spectra showed the sharp peaks and circumstellar dust exist in low temperature as several 10 K. In universe, Mg elements and Fe elements are equally exist. So, it is very important to study how the spectra depend on Mg/Fe ratio. With our measurements of infrared spectra of olivine and pyroxene, the spectra were depend on Mg/Fe ratio, and peak positions are shifted to longer wavelength as Mg content decreases. Particularly, end members are very sensitive to Mg/Fe ratio, and peak shifts are drastically changed as this ratio. We detected diopside around evolved objects comparing with observed broad band at about 65 μm and laboratory measured data. This broad band was thought to originate to water ice, but water ice shows peak at around 62 μm even cooled to various temperature. Since our detected diopside, many workers noticed both of high and low temperature condensation minerals, and some group detected carbonate minerals such as calcite and dolomite. Recently, many new discover of minerals according to condensation theory are showed, and identification of observed bands and evolution of materials are very interesting.