Dust Polarization in Four Protoplanetary Disks at 3 mm: Further Evidence of Multiple Origins

Rachel E. Harrison, Leslie W. Looney, Ian W. Stephens, Zhi Yun Li, Haifeng Yang, Akimasa Kataoka, Robert J. Harris, Woojin Kwon, Takayuki Muto, Munetake Momose

Research output: Contribution to journalArticlepeer-review


We present polarimetric observations of four Class II protoplanetary disks (DG Tau, Haro 6-13, RY Tau, and MWC 480) taken with the Atacama Large Millimeter/submillimeter Array (ALMA) at 3 mm. The polarization morphologies observed fall into two distinct categories: azimuthal polarization (DG Tau and Haro 6-13) and polarization parallel to the disk minor axis (RY Tau and MWC 480). The mechanisms responsible for disk polarization at millimeter and submillimeter wavelengths are currently under debate. In this Letter, we investigate two mechanisms capable of producing polarized dust emission in disks: self-scattering and grain alignment to the radiation anisotropy. The polarization morphologies of DG Tau and Haro 6-13 are broadly consistent with that expected from radiation alignment (though radiative alignment still does not account for all of the features seen in these disks), while RY Tau and MWC 480 are more consistent with self-scattering. Such a variation in the polarized morphology may provide evidence of dust grain size differences between the sources.

Original languageEnglish (US)
Article numberL2
JournalAstrophysical Journal Letters
Issue number1
StatePublished - May 20 2019


  • polarization
  • protoplanetary disks
  • scattering
  • stars: protostars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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