@article{e156871528b2484cb8a1af5a5de3b380,
title = "Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. II. IRAS 16293-2422",
abstract = "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 Alfv{\'e}n 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.",
keywords = "ISM: magnetic fields, dust, extinction, polarization, stars: formation, stars: protostars",
author = "Sadavoy, {Sarah I.} and Myers, {Philip C.} and Stephens, {Ian W.} and John Tobin and Woojin Kwon and Dominique Segura-Cox and Thomas Henning and Benoit Commer{\c c}on and Leslie Looney",
note = "We thank the anonymous referee for comments that helped improve the discussion. The authors also acknowledge the NAASC and EU-ARC for support with the ALMA observations and data processing. The authors thank Shantanu Basu, Sebastien Fromang, Lee Hartmann, Patrick Hennebelle, Zhi-Yun Li, Stella Offner, and Anna Rosen for insightful theoretical discussions on magnetic fields in protostellar systems and filaments, and Ted Bergin, Jes J{\o}rgensen, and Matthijs van der Wiel for valuable discussions on the kinematic and physical properties of the dust and gas in the Bridge. S.I.S. acknowledges the support for this work provided by NASA through Hubble Fellowship grant No. HST-HF2-51381.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract No. NAS 5-26555. W.K. was supported by Basic Science Research Program through the National Foundation of Korea (grant No. NRF-2016R1C1B2013642). L.W.L. acknowledges the support of NASA/JPL through the grant No. 1594465. This paper makes use of the following ALMA data: ADS/JAO. ALMA#2015.1.01112.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.",
year = "2018",
month = dec,
day = "20",
doi = "10.3847/1538-4357/aaef81",
language = "English (US)",
volume = "869",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "American Astronomical Society",
number = "2",
}