SUBARU IMAGING OF ASYMMETRIC FEATURES IN A TRANSITIONAL DISK IN UPPER SCORPIUS

We report high-resolution (0.07 arcsec) near-infrared polarized intensity imagesof the circumstellar disk around the star 2MASS J16042165-2130284 obtainedwith HiCIAO mounted on the Subaru 8.2 m telescope. We present ourH-band data, which clearly exhibits a resolved, face-on disk with a large innerhole for the first time at infrared wavelengths. We detect the centrosymmetricpolarization pattern in the circumstellar material as has been observed in otherdisks. Elliptical fitting gives the semimajor axis, semiminor axis, and positionangle (P.A.) of the disk as 63 AU, 62 AU, and -14 ◦, respectively. The disk isasymmetric, with one dip located at P.A.s of 85◦. Our observed disk size agreeswell with a previous study of dust and CO emission at submillimeter wavelengthwith Submillimeter Array. Hence, the near-infrared light is interpreted as scatteredlight reflected from the inner edge of the disk. Our observations also detectan elongated arc (50 AU) extending over the disk inner hole. It emanates at theinner edge of the western side of the disk, extending inward first, then curving tothe northeast. We discuss the possibility that the inner hole, the dip, and the arcthat we have observed may be related to the existence of unseen bodies withinthe disk