Near-Infrared Coronagraphy of the GG Tauri A Binary System

The highest angular resolution near-infrared images of the GG Tau A binary system were obtained with the Coronagraphic Imager with Adaptive Optics (CIAO) mounted on the Subaru Telescope. The images show that its circumbinary disk is smooth and does not have 0. 1 scale structures. Asymmetries in the surface brightness as well as a gap are also resolved. Combined with previous measurements of the stellar positions, our data indicate that the central binary is unlikely to have a large eccentricity. The fifth point source toward this double binary system is probably a background star, based on astrometric measurements.