Authors

J. Hashimoto(1), M. Tamura(1), T. Muto(2), T. Kudo(1), M. Fukagawa(3), T. Fukue(1), C. Grady(4), T. Henning(5), K. Hodapp(6), M. Honda(7), S. Inutsuka(8), E. Kokubo(1), G. Knapp(9), M. W. McElwain(9), M. Momose(10), N. Ohashi(11), Y. K. Okamoto(10), M. Takami(11), E. L. Turner(9,12), J. Wisniewski(13), M. Janson(14), and HiCIAO/AO188/SEEDS members

Affiliations

(1)National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan (2)Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551, Japan (3)Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043, Japan (4)Eureka Scientific and Goddard Space Flight Center, Greenbelt, USA (5)Max Planck Institute for Astronomy, Heidelberg, Germany (6)University of Hawaii,640 North A’ohoku Place, Hilo, HI 96720, USA (7)Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan (8) Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan (9)Department of Astrophysical Sciences, Princeton University, NJ 08544, USA (10)Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki, 310-8512, Japan (11)Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (12)Institute for the Physics and Mathematics of the Universe, The University of Tokyo, Kashiwa 227-8568, Japan (13)University of Washington, Seattle, Washington, USA (14)University of Toronto, Toronto, Canada

Abstract

We present the results of the high-resolution near-infrared dual-beam polarimetry of the circumstellar disk around AB Aur (2.4 Mo) using a new high contrast instrument HiCIAO mounted on the Subaru 8.2 m telescope.

As a result of stellar evolution, it is widely known that planets are formed in circumstellar disks around young stars. Thus, investigating the detailed structures of circumstellar disks and their evolutions are of great importance in understanding the nature of planet formation mechanisms. However, since the speckle noise is dominant in the inner disk regions (r <1 arcsec) around bright central young star, the observations at the planet forming radius (r <100 AU) are quite challenging so far. The dual-beam polarimetry enable us to suppress the speckle noise and to approach the inner disk regions tens AU in nearby star forming regions.

Thanks to the better polarimetry performance of both the inner working angle (22 AU) and the resolution (9 AU) at the distance of AB Aur, we detect the rich structure including a bumpy double ring and a ring-like gap at the possible giant-planet location. Our results suggest giant-planet formation in the disk and provides essential information for understanding disk instability and planet formation models.