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We conduct observational research to investigate formation process of extrasolar planets as well as galaxy formation and starburst phenomena. In these astronomical phenomena, small solid particles (interstellar dust grains) play important roles in energy conversion and various chemical reactions in space. As the dust grains reradiate absorbed energy mainly in the infrared domain, precise infrared observations provide us valuable information to elucidate important physical processes in space. The longer wavelength part of infrared (far-infrared) cannot be observed from the ground because the earth's atmosphere is completely opaque. Therefore, we mount the far-infrared telescopes on artificial satellites or scientific balloons, and execute precise observations in space. In particular, we are developing a far-infrared astronomical interferometer for the first time in the world so as to achieve a spatial resolution more than ten times higher than previously obtained. We also perform near-infrared high-contrast observations of protoplanetary disks and young, gaseous giant extrasolar planets using the Subaru telescope in Hawaii.
- Infrared observations of extrasolar planets and protoplanetary/debris disks
- Study on interstellar dust grains in galaxy formation/starburst phenomena
- Development of far-infrared interferometer for astronomy
FITE (Far-Infrared Interferometric Telescope Experiment) is a balloon-borne instrument equipped with a Michelson interferometer, and will achieve the tremendous spatial resolution in far-infrared, about 1 arcsec at 100 micron. It will open a new frontier to study dusty universe in far infrared. The first light is scheduled in the fall of 2010.
MOA (Microlensing Observations in Astrophysics)
The MOA project is a collaboration between Japan and New Zealand which searches for extrasolar planets via gravitational microlensing.
Gravitational microlensing occurs when the light from a background star (the source star) is deflected by the gravitational potential of a foreground star (the lens star). This causes the light from the source star to appear brighter, leading to a time dependent magnification of the source star.
If the lens star hosts a planet, and if the planet also passes close to the light given off by the source star, the planet will also act as a lens, resulting in a characteristic, short-lived signal in the primary magnification.
Through a detailed analysis of the light curve of a planetary microlensing event, we can derive certain important physical characteristics of the planet, such as its mass or its separation from its host star.
Also this method is sensitive to free floating planets.
Our observations focus on microlensing events in the Galactic bulge and are conducted using the 1.8m MOA-II telescope at Mt.John observatory in New Zealand.
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SEEDSiStrategic Exploration of Exoplanets and Disks with HiCIAO/AO188j
We join the SEEDS project to study extrasolar planets and protoplanetary/debris disks. The imaging observations will be carried out with the near-infrared camera HiCIAO on the Subaru Telescope. The state-of-art instrument will provide us the images of extrasolar planets with its high-contrast and high spatial resolution. The science observations have started from October 2009.