Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. II. IRAS 16293-2422

Sarah I. Sadavoy, Philip C. Myers, Ian W. Stephens, John Tobin, Woojin Kwon, Dominique Segura-Cox, Thomas Henning, Benoit Commerçon, Leslie Looney

Research output: Contribution to journalArticlepeer-review


We present high-resolution (∼35 au) ALMA Band 6 1.3 mm dust polarization observations of IRAS 16293. These observations spatially resolve the dust polarization across the two protostellar sources and toward the filamentary structures between them. The dust polarization and inferred magnetic field have complicated structures throughout the region. In particular, we find that the magnetic field is aligned parallel to three filamentary structures. We characterize the physical properties of the filamentary structure that bridges IRAS 16293A and IRAS 16293B and estimate a magnetic field strength of 23-78 mG using the Davis-Chandrasekhar-Fermi method. We construct a toy model for the bridge material assuming that the young stars dominate the mass and gravitational potential of the system. We find that the expected gas flow to each star is of comparable order to the Alfvén speed, which suggests that the field may be regulating the gas flow. We also find that the bridging material should be depleted in ∼103 yr. If the bridge is part of the natal filament that formed the stars, then it must have accreted new material. Alternatively, the bridge could be a transient structure. Finally, we show that the 1.3 mm polarization morphology of the optically thick IRAS 16293B system is qualitatively similar to dust self-scattering. Based on similar polarization measurements at 6.9 mm, we propose that IRAS 16293B has produced a substantial population of large dust grains with sizes between 200 and 2000 μm.

Original languageEnglish (US)
Article number115
JournalAstrophysical Journal
Issue number2
StatePublished - Dec 20 2018


  • ISM: magnetic fields
  • dust, extinction
  • polarization
  • stars: formation
  • stars: protostars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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