Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 2B022

Near-Infrared Polarimetric Imaging of Disks around Young Intermediate-mass Stars in SEEDS

Fukagawa, Misato (Osaka University)
Hashimoto, Jun (The University of Oklahoma)
Grady, C. A. (Eureka Scientific/GSFC)
Momose, Munetake (Ibaraki University)
Wisniewski, J. P. (The University of Oklahoma)
Okamoto, Yoshiko (Ibaraki University)
Muto, Takayuki (Kogakuin University)
Kusakabe, Nobuhiko (NAOJ)
Bonnefoy, Mickael (MPIA)
Kotani, Takayuki (NAOJ)
Maruta, Yayoi (Osaka University)
Tamura, Motohide (The University of Tokyo)
SEEDS/HiCIAO/AO188 collaboration, ()

We present our recent results to directly image circumstellar disks around Herbig Fe/Ae/Be stars in scattered light with Subaru. Observations of such young disks are critically important to understand how disks evolve possibly under the mutual interaction with new-born planets. One of the observational approaches is direct imaging in scattered light, and the progress in this field since PPV can be found in the ability to prove inner regions of disks. This improvement largely owes to the technique of polarization differential imaging (PDI) which provides higher contrast by extracting scattered light from the disk while suppressing unpolarized stellar light. Strategic Exploration of Exoplanets and Disks with Subaru (SEEDS) is the project dedicated to exoplanet hunting and study of circumstellar disks by direct imaging. Since its beginning in 2009, thirteen Herbig Fe/Ae/Be stars have been observed primarily in H band (1.6 micron). The PDI method has been employed with adaptive optics, enabling us to look into the inner region as close as 0.2 arcsec (∼30 AU) in radius with the typical angular resolution of 0.06 arcsec (∼8 AU). As a result, the SEEDS imagery has newly uncovered rich structures such as spiral arms, inner holes, and gaps for (pre-)transitional disks while suggested the variably illuminated disks for primordial systems. The highlight is the discovery of two spiral arms each for SAO 206462 and MWC 758. The spiral feature has been uniquely found toward Herbig Fe/Aes so far, which might be due to their warmer disks producing arms loosely wound and more easily detected. The observed morphology can be interpreted by the density-wave model, and those disks are implied to harbor Jupiter-mass companions as the exciting sources of the spiral structures according to these models.

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