A Study of Interstellar Dust Grains based on the Diffuse Galactic Light

我们成功地完成了IRTS(太空红外望远镜)的任务，该任务于1995年3月18日由HII-3火箭发射。IRTS上搭载的中红外光谱仪(MIRS)观测到了漫射银河光的约7个分辨率光谱，首次提供了黄道光和漫射银河光的中红外光谱。我们在发射前准备了几个软件，以制定观测计划并确认MIR的飞行性能。基于飞行后的数据分析，我们清楚地表明，围绕银河平面的中红外漫反射光由6.2、7.7、8.6和11.3毫米的所谓红外不明波段(UIR)组成。这表明UIR发射物质在星际空间中普遍存在，被认为是碳质物质，为星际尘埃颗粒模型的研究提供了关键信息。结合MIRS数据的约化，我们对COBE数据进行了分析，发现中红外漫射辐射与星际辐射场的强度成正比，这支持了这种辐射的温度波动甚小尘埃颗粒模型。在此研究的同时，我们还证明了热发射的偏振可以提供将漫反射发射分成几个组分的信息。综上所述，我们明确建立了利用弥散背景辐射研究星际尘埃粒子的新的观测方法，实现了本项目的主要目标。我们计划对MIRS数据进行进一步的分析，并继续进行星际尘埃颗粒的调查。

We had a successful mission of the IRTS (InfraRed Telescope in Space), which was launched by the HII-3 rocket on March 18,1995. The IRTS observed about 7 resolution spectra of the diffuse Galactic light by the Mid-InfraRed Spectrometer (MIRS) aboard the IRTS.These provide the mid-IR spectra of the zodiacal light and the diffuse Galactic Light for the first time. We prepared several pieces of software prior to the launch in order to make the observation plan and confirm the flight performance of the MIRS.Based on the post-flight data analysis, we have clearly shown that the mid-infrared diffuse light around the Galactic plane consists of the so-called infrared unidentified bands (UIRs) of the 6.2,7.7,8.6, and 11.3 mm. This suggests the ubiquitous existence of the UIR emitting material in the interstellar space, which is thought to be carbonaceous material and provides key information for the investigation of the interstellar dust grain models. Together with the MIRS data reduction, we have analyzed the COBE data, finding that the mid-IR diffuse emission is proportional to the strength of the interstellar radiation field, which supports the temperature-fluctuating very small dust grain model for this emission. In parallel to this research, we have also shown that the polarization of the thermal emission could provide the information to separate the diffuse emission into several components. In summary, we have clearly established the new observational method for the research of interstellar dust grains by using the diffuse background emission and achieved the primary goal of this project. We are planning to make further analysis of the MIRS data and pursue the investigation of interstellar dust grains.