DIRECT IMAGING OF FINE STRUCTURES IN GIANT PLANET-FORMING REGIONS OF THE PROTOPLANETARY DISK AROUND AB AURIGAE

Abstract

We report high-resolution 1.6 μm polarized intensity (PI) images of the circumstellar disk around the Herbig Ae star AB Aur at a radial distance of 22 AU (0farcs15) up to 554 AU (3farcs85), which have been obtained by the high-contrast instrument HiCIAO with the dual-beam polarimetry. We revealed complicated and asymmetrical structures in the inner part (lsim140 AU) of the disk while confirming the previously reported outer (r >~ 200 AU) spiral structure. We have imaged a double ring structure at ~40 and ~100 AU and a ring-like gap between the two. We found a significant discrepancy of inclination angles between two rings, which may indicate that the disk of AB Aur is warped. Furthermore, we found seven dips (the typical size is ~45 AU or less) within two rings, as well as three prominent PI peaks at ~40 AU. The observed structures, including a bumpy double ring, a ring-like gap, and a warped disk in the innermost regions, provide essential information for understanding the formation mechanism of recently detected wide-orbit (r > 20 AU) planets. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.