Visit ASIAA Homepage Registration Deadline: November 27, 2019 (Taiwan Time)
East-Asian ALMA Science Workshop 2019
February 19(Wed)-21(Fri), 2020
ASIAA, Taipei, Taiwan

Poster Presentation

Dust polarization in the circumternary disk GG Tau A system

Author(s): Ya-Wen Tang, Robert Brauer, Stephane Guilloteau, Akimasa Kataoka, Patrick Koch, Anne Dutrey, Takayuki Muto, Hiroyuki Hirashita

Presenter: Ya-Wen Tang (ASIAA)

Recent ALMA observations of the continuum polarization in several circumstellar disks have demonstrated that dust self-scattering at millimeter wavelengths can be important in disks.
For example, due to the large (~100 au in radius) central cavity, dust grains on the dust ring of HD 142527 produce anisotropic
self-scattering and thus cause a flip in the position angle of polarization across the dust ring along radius.
The degree of polarization is, however, more complex than the predictions from a simple self-scattering model.
Spatially resolved and multi-wavelength observations of the polarization are a new powerful tool to constrain the grain size distribution in protoplanetary disks.
Contrary to HD 142527, the GG Tau A system is surrounded by a uniform ring, where the width extends from 180 to 260 au in radius.
This makes GG Tau A system a relatively clean target to test the origin of polarization at mm/submm, to study the distribution of grain size and to study any underlying sub-features.
In this poster, we will present our ALMA polarization results at the resolution of 0.3" in band 7 and 0.6" in band 3.
The band 7 results are consistent with what is predicted in the self-scattering model. However, we found that there is a systematic deviation from elliptical in the band 3 data. Possible mechanisms to cause this pattern are discussed.

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