Oral Presentation

ALMA polarization observations toward the protoplanetary disk around HD 142527

Author(s): Satoshi Ohashi (RIKEN), Akimasa Kataoka (National Astronomical Observatory of Japan), Hiroshi Nagai (National Astronomical Observatory of Japan), et al.

Presenter: Satoshi Ohashi (RIKEN)

We present new ALMA polarization observations of 0.87 mm dust continuum emission toward the circumstellar disk around HD 142527, having lopsided intensity distribution.
The beam size is 0.27" x 0.24", corresponding to the spatial resolution of 38 x 34 au, which is the highest resolution in polarization observation so far.
We confirm that the polarization intensity shows the ring-like structure.
The polarization vector mainly indicates the radial direction in this ring, but the azimuthal direction is found outside northern part.
This flip of the polarization vector from radial to azimuthal direction can be explained by the self-scattering of thermal dust emission as suggested by Kataoka et al. (2016).
However, the southern area shows only the radial direction of the polarization vectors and the polarization fraction is as high as 15%. It is unlikely to explain the polarization vectors and high polarization fraction due to the self-scattering.
We discuss other possibilities of the polarization mechanism due to the dust alignment by the magnetic field or by the radiation field.
The difference in the polarization fraction suggests that the polarization mechanism differ from north to sough area and depends on the dust properties.