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

Abstract

We report high-resolution 1.6 $\\micron$ polarized intensity ($PI$) images of\nthe circumstellar disk around the Herbig Ae star AB Aur at a radial distance of\n22 AU ($0."15$) up to 554 AU (3.$"$85), which have been obtained by the\nhigh-contrast instrument HiCIAO with the dual-beam polarimetry. We revealed\ncomplicated and asymmetrical structures in the inner part ($\\lesssim$140 AU) of\nthe disk, while confirming the previously reported outer ($r$ $\\gtrsim$200 AU)\nspiral structure. We have imaged a double ring structure at $\\sim$40 and\n$\\sim$100 AU and a ring-like gap between the two. We found a significant\ndiscrepancy of inclination angles between two rings, which may indicate that\nthe disk of AB Aur is warped. Furthermore, we found seven dips (the typical\nsize is $\\sim$45 AU or less) within two rings as well as three prominent $PI$\npeaks at $\\sim$40 AU. The observed structures, including a bumpy double ring, a\nring-like gap, and a warped disk in the innermost regions, provide essential\ninformation for understanding the formation mechanism of recently detected\nwide-orbit ($r$ $>$20 AU) planets.\n