MID-INFRARED SPECTROSCOPIC STUDY OF BRIGHT INFRARED GALAXIES

这项研究的一个独特的技术方面是开发一个中红外法布里-珀罗成像仪（MIRFI），这是专为地面观测中红外光谱线位于10微米的大气窗口。MIRFI由光谱分辨率为-2500的扫描法布里-珀罗干涉仪和Si：P光电导探测器阵列（5 × 5格式）组成，两者都用液氦冷却，用于观察氖离子的[Ne Ⅱ] 12.814 μ m谱线。获得的1.6 × 10^<-20>Wcm^<-2>pixel^<-1>（每光谱分辨率，17秒积分）的灵敏度足以观测到具有星星爆发形成的近红外星系（星暴星系）的[Ne II]线，本研究的主要科学目标是利用[Ne II]线研究近星暴星系的中心区结构。红外发光的星暴星系被尘埃严重遮蔽，因此在光学波长下不可见，但在12.8 μ m的尘埃消光几乎可以忽略不计。1995年4月，我们与美国航天局/国际热带天文台（美国夏威夷莫纳克亚山）进行了第一次观测，但由于天气恶劣，没有科学数据。1996年3月、10月和1997年3月，我们与美国怀俄明州的怀俄明州红外天文台进行了连续观测，最终探测到了来自星暴星系M82的[Ne II]线，以及银河系超紧H II区（W 51 d，G 29.96 -0.02等）丰富的[Ne II]通量数据。我们无法获得太多红外星系的数据：要做到这一点，我们需要非常好的天气条件。然而，MIRFI被证明是有效的工作，对银河系天体的观测，并将在不久的将来提供更多的科学成果。

A unique technical aspect of this research is to develop a Mid-Infrared Fabry-Perot Imager (MIRFI), which is designed for ground-based observations of mid-infrared spectral lines located in the 10mum atomospheric window. MIRFI is now tuned to observe [Ne II] 12.814mum line from neon ions, and consists of a scanning Fabry-Perot interferometer with a spectral resolving power of -2500 and a Si : P photoconductive detector array (5x5 format), both are cooled by liquid-He. Achieved sensitivity of 1.6*10^<-20> Wcm^<-2>pixel^<-1> (per spectral resolution, 17sec integration) is sufficient to observe the [Ne II] line from neaby bright infrared galaxies with burst of star formation (starburst galaxies).Major scientific goal of this research is to investigate the structure of central region of neaby starburst galaxies by the [Ne II] line. Infrared luminous starburst galaxies are heavily obscured by dust and hence are not visible at optical wavelenth, but at 12.8mum dust extinction is almost negligible. We have made the first observing run with NASA/IRTF (Mauna Kea, Hawaii, USA) in April 1995, but no scientific data due to bad weather. In March and October 1996, and March 1997, we have made observing runs with Wyoming Infrared Observatory (Wyoming, USA), and finally detected [Ne II] line from the starburst galaxy M82, as well as rich [Ne II] flux data for Galactic ultracompact H II regions (W51d, G29.96-0.02, etc.). We could not obtain much data for infrared galaxies : to do this we need very good weather condition. However, MIRFI is proved to work efficiently for observation of Galactic objects and will provide much scientific results in the near future.