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Paper: High-Angular-Resolution Infrared Observations of Protoplanetary Disks
Volume: 476, New Trends in Radio Astronomy in the ALMA Era
Page: 157
Authors: Fukagawa, M.; Hashimoto, J.; Tamura, M.; SEEDS/HiCIAO/IRCS/AO188
Abstract: Observations of protoplanetary disks are essential to understand planet building process since they provide realistic initial conditions as well as insights into new-born planets through disk-planet dynamical interaction. Scattered-light observations at optical and near-infrared are complementary with longer-wavelength studies as they can provide the information on smaller grains in disks, thus useful to discuss such as grain growth and dust transport that can be either the basic step toward or the consequence of planet-forming activity. As a part of Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS), we have observed more than 60 T Tauri and Herbig Ae/Fe stars. Our targets include transitional systems showing the dips in the mid-infrared SEDs and/or the resolved cavities in submillimeter. The technique of polarization differential imaging (PDI) was employed combined with adaptive optics for most cases in order to achieve high contrast by extracting the scattered light from the disk while suppressing the unpolarized stellar light. The PDI observations indeed enabled us to look at the inner region, as close as about 20 AU in radius typically, with the angular resolution of 0.06 arcsec, corresponding to less than 10 AU in nearby star-forming regions. As a result, the SEEDS imaging has newly uncovered rich structures such as spirals, inner holes, and gaps for transitional systems. The highlight is the discovery of two spiral arms in the submillimeter cavity for SAO 206462, and the subsequent finding of similar spirals for MWC 758, which can be explained by possible presence of giant planets. The comparable angular resolution will be achieved in submillimeter soon with ALMA, and multi-wavelength study will become more important for comprehensive understanding of disks.
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