Space Infrared Study of Evolution of Planetary Systems : from Disks to Planets

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The infrared astronomical satellite IRAS found about 10 main sequence stars with far infrared excess, which invoked many discussions on the formation and evolution of circum-stellar dust disks (so-called debris disks) around main-sequence stars. The debris disks are believed to have strong connection with the formation and evolution on planetary systems.One of the objectives of the current research is to increase the number of observations of debris disks significantly, which could enable statistical study of evolution of debris disks. For this purpose, we had been working on a Japanese infrared astronomical satellite program ASTROF. ASTROF was launched successfully in February 2006, and started all-sky survey observations, which are expected to bring us a new catalog of debris disks. We mainly worked on the planning of effective observations and the development of data reduction software tools for the all sky survey, both of which worked effectively for real observations.To supplement space-borne observations, we also used ground-based telescopes for high-resolution observations of debris disks. One of the most important discoveries is the observational evidence for the presence of planets around beta Pic.We also worked on the development of stellar coronagraphs for the direct detection of exoplanets with future missions. We fabricated a special binary shaped pupil, and achieved a contact of 10^7, which was a world record of contract without wavefront control. We also worked on Phase-Induced Amplitude Apodization coronagraphs to reduce the inner working angle (IWG), which is an important technique to enable the detection of exoplanets close to central stars.