Direct Imaging of Fine Structures in Giant Planet-Forming Regions of the Protoplanetary Disk Around Ab Aurigae

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 (0 15) up to 554 AU (3 85), 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 (≲140 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.