Observational Study on the Evolution of Galaxy Structure

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We carried out the collaborative research with University of Hawaii by sending 35 teams in total to Hawaii. Using mainly UH telescopes and other telescopes on Mauna Kea, in conjunction with Japanese instruments, we performed various observations to investigate structure of the Galactic center, structure of galaxies, and structure of star forming regions. Main results are as follows :The observation was made using a NIR camera with PtSi detector. This NIR camera with 512X512 pixels had the widest FOV and was most effective to reveal wide-area structures around the Galactic center. The result indicated that the absorption features coincided with those of, dense molecular clouds.Using UH FOS we observed compact groups of galaxies to determine their structure and kinematic properties, and to find out strong environmental effect on the evolution of galaxies by computer simulations based upon the observational results. It was suggested that wide distributed dark matter may suppress the too quick evolution. Surface photometric study of edge-on galaxies revealed that some of disks showed warping which was attributed to tidal interaction with another galaxies. NIR disk images revealed multiple scale heights in their vertical structure. Dust emission was investigated using prism- and grating spectrometers developed in Japan. Many of IRAS galaxies showed 3.3mum emission correlated to star formation activity. Thermal component of 1500K was detected from QSO's.The same spectrometers were used for investigation of circumstellar physics of young stellar objects. FU Ori objects showed watervapour absorption when they were in flare-up phase, indicating that intensitiedradiation evaporated ice grains. 4 of IRAS sources showed 3mum dust emission, similar to that seen from scattering nebulae.A mm-wave polarimetry indicated interstellar magnetic field perpendicular to the disk plane of a law-mass protostellar disk cloud.