Far-Infrared Observation of Metal-Poor Interstellar Medium

本研究的目的是利用远红外线光谱诊断邻近星系的星际气体，了解星系星际空间的电离/离解结构以及能量传递流。首先，我们研制了一种新型的反射光栅--浸没光栅1，它虽然具有较高的光谱分辨率，但体积较小。通过使用折射率为3.4的硅，用10厘米光栅实现了10，000的光谱分辨率。抗反射涂层在技术上也是可行的。我们已经通过开发这种测量所需的新装置，在低温（4K）下测量了实际用于光栅的大硅材料的透射率，结果超过50%。同时，通过对ISO（ESA）卫星观测数据的分析，我们对船底座区这一典型的大尺度恒星形成区的星际空间硅丰度有了重要的认识。我们还发现了一种新的方法来估计星际尘埃颗粒的物理特性，从一个在远红外区的观测数据较少。这些结果已提交给主要期刊。

The purpose of this research is to diagnose interstellar gas in nearby galaxies and to understand the ionization/dissociation structure of the interstellar space of the Galaxy as well as the energy transfer flow there by line spectroscopy in the far-infrared region.At first, we have developed a new type reflection grating, 'immersion grating1, which is relatively small although it has higher spectral resolution. By using silicon whose refractive index is 3.4, the spectral resolving power of 10,000 is achieved with a 10 cm grating. The anti-reflection coating is also technically feasible. We have measured the transmission of a large silicon material that is to be actually used for the grating at a cryogenic temperature (4K) by developing a new device that is necessary for this kind of measurement, and the result is more than 50 %. Moreover, we designed a two-dimensional array as well as a cryogenic optical system for the spectrometer.In parallel to this, by analyzing the data taken by the ISO (ESA) satellite, we have an important knowledge about the silicon abundance in the interstellar space of the Carina region, a typical large-scale star-forming region. We also found a new method to estimate the physical characteristics of the interstellar dust grain from a fewer observational data in the far-infrared region. These result were submitted to main journals.