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

自ISO（红外天文台）观测以来，在年轻天体和演化天体的星周各处都发现了结晶硅酸盐。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化和尘埃的质量，需要有各种物质的光学性质的良好数据。但是，只有很少的数据可以公布。结晶硅酸盐是富镁的，如镁橄榄石Mg_2SiO_4和顽火辉石MgSiO_3。将橄榄石和辉石粒子冷却到液氦温度，峰位向短波长移动，峰变得尖锐。这与观测结果一致，即谱图显示在10 K左右的低温下有尖峰和星周尘埃存在。在宇宙中，Mg元素和Fe元素是平等存在的。因此，研究Mg/Fe比对光谱的影响是非常重要的。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比有关，并且随着Mg含量的降低，红外光谱的峰位向长波方向移动。特别地，端元对Mg/Fe比非常敏感，并且峰位移随着该比而急剧变化。通过与观测到的65 μm左右的宽谱带和实验室测量数据的比较，在演化天体周围发现了透辉石。这一宽带被认为是水冰的起源，但水冰即使冷却到不同温度也会在62 μm左右出现峰值。自从我们发现透辉石以来，许多工作者都注意到了高温和低温冷凝矿物，也有一些工作者发现了碳酸盐矿物，如方解石和白云石。近年来，根据凝聚理论发现了许多新的矿物，对观测到的谱带进行了识别，并对物质的演化进行了研究。

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.