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

远红外区星周及星际尘埃候选材料光学特性测量及其在红外天文学中的应用

基本信息

批准号：
12440054
负责人：
KOIKE Chiyoe
金额：
$ 10.56万
依托单位：
Kyoto Pharmaceutical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

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.

自从ISO（天文台红外空间）观测以来，在年轻天体和演化天体的星周各处都检测到了结晶硅酸盐。这些事实与无定形尘埃的传统观念相矛盾。为了明确灰尘物质的演化过程和灰尘的质量，需要各种材料的光学特性的良好数据。但是，只能发布很少的数据。结晶硅酸盐富含镁，例如镁橄榄石Mg_2SiO_4和顽辉石MgSiO_3。将橄榄石和辉石颗粒冷却到液氦温度，峰位置移动到更短的波长，并且峰变得更尖锐。这与观测结果相同，光谱显示在几十K的低温下存在尖峰和星周尘埃。在宇宙中，Mg元素和Fe元素同样存在。因此，研究光谱对 Mg/Fe 比的影响非常重要。通过我们对橄榄石和辉石红外光谱的测量，光谱取决于 Mg/Fe 比率，并且随着 Mg 含量的降低，峰位置移动到更长的波长。特别是，端元对 Mg/Fe 比率非常敏感，并且峰移随着该比率而急剧变化。我们在演化物体周围检测到透辉石，与观察到的约 65 μm 的宽带和实验室测量的数据进行比较。这条宽带被认为起源于水冰，但水冰即使冷却到不同的温度，在 62 μm 附近也显示出峰值。自从我们检测到透辉石以来，很多工作人员都注意到了高温和低温凝结矿物，还有一些小组检测到了方解石、白云石等碳酸盐矿物。近年来，根据凝聚理论发现了许多矿物的新发现，观测带的识别和物质的演化非常有趣。