Optical properties of candidate minerals for circumstellar dust in the UV - Far infrared region and application for Infrared Astronomy

对于星周尘埃的各种候选材料，我们研究了温度对细颗粒红外光谱的影响。特别是温度对橄榄石粒子从室温冷却到10 K左右的光谱的影响，各峰的强度和半宽分别变强和变窄，各峰的位置向更短的波长移动。这些趋势在中红外区比较温和，但在远红外区非常明显。特别是对橄榄石来说，49 μm和69μm的位置和半宽成为温度指标。也就是说，任何观测者都可以从观测位置和星周或星际区域的半宽度得知尘埃温度。我们在橄榄石端部附近合成了橄榄石样品，发现49 μm和69μm的峰随着铁含量的变化变化很大。进一步合成了含有Ca、Na、Al、a、More等元素的硅酸盐晶体，并明确了其峰位与成分的关系。采用溶胶-凝胶法制备了具有球粒体成分的非晶态硅酸盐，研究了退火后红外光谱的变化，明确了结晶过程。对于大块的橄榄石样品，从每一次测得的中、远红外反射率都可以得到满意的各轴光学常数。在此基础上，将样品连续冷却至10 K左右，测量了样品在中、远红外3轴的反射率。然后，我们从多个低温下的反射率得到了各轴的光学常数。69μm波段的反射率在10 K时的强度是常温下的3倍。另一个远红外峰也显示出类似的趋势。我们明确了每个轴的光学常数取决于温度。根据光学常数，任何人都可以计算出各种形状的光谱，如针形、扁形、比例形和苍白形。在室内试验中，确定了椭圆形和茎状花的形状效应。少

For various candidates materials for circumstellar dusts, we investigated the temperature effects on infrared spectra of fine particles. Especially, as for temperature effects on spectra of olivine particles cooling down from room temperature to about 10 K, the intensity and half width of each peak became strong and narrow, respectively, and the position of each peak shifted to shorter wavelength. These tendencies were gentle in mid infrared region, but were very distinct in far infrared region. In particularly for the case of forsterite, the position and half width of 49 and 69μm were shown to be become the temperature indicator. That is, any observer can know the dust temperature from the observed position and half width in circumstellar or interstellar region.We synthesized olivine samples near end member of forsterite and made clear that the 49 and 69μm peak changed drastically according to the Fe content. Further we synthesized silicate crystalline including Ca, Na, Al elements, a … More nd the correlation between peak position and composition was made clear. Amorphous silicates with chondritic components were synthesized by Sol-Gel method, and the process to crystallization was made clear studying the change of infrared spectra after annealing.As for bulk sample of forsterite, we can obtained the satisfactory optical constants for each axis from each measured reflectance in mid and far infrared. Further, cooling the bulk sample of forsterite continuously to about 10 K, the reflectance were measured in mid and far infrared region for 3 axis. Then, we obtained the optical constants for each axis from the reflectance at many low temperature. As for the reflectance of 69μm band, the intensity become 3 times at 10 K compared to at room temperature. Another peaks at far-infrared also showed similar tendencies. We made clear the optical constants for each axis depend on temperature. From the optical constants, anyone can calculate the spectra in various shape such as needle, oblate, prorate and pale. The shape effects were ascertained in laboratory in the case of ellipse and cauli flower of forsterite. Less