JCMT POL-2 and ALMA polarimetric observations of 6000-100 au scales in the protostar B335: linking magnetic field and gas kinematics in observations and MHD simulations

Abstract

We present our analysis of the magnetic field structures from 6000 au to 100 au scales in the Class 0 protostar B335 inferred from our JCMT POL-2 observations and the ALMA archival polarimetric data. To interpret the observational results, we perform a series of (non-)ideal MHD simulations of the collapse of a rotating non-turbulent dense core, whose initial conditions are adopted to be the same as observed in B335, and generate synthetic polarization maps. The comparison of our JCMT and simulation results suggests that the magnetic field on a 6000 au scale in B335 is pinched and well aligned with the bipolar outflow along the east-west direction. Among all our simulations, the ALMA polarimetric results are best explained with weak magnetic field models having an initial mass-to-flux ratio of 9.6. However, we find that with the weak magnetic field, the rotational velocity on a 100 au scale and the disk size in our simulations are larger than the observational estimates by a factor of several. An independent comparison of our simulations and the gas kinematics in B335 observed with the SMA and ALMA favors strong magnetic field models with an initial mass-to-flux ratio smaller than 4.8. We discuss two possibilities resulting in the different magnetic field strengths inferred from the polarimetric and molecular-line observations, (1) overestimated rotational-to-gravitational energy in B335 and (2) additional contributions in the polarized intensity due to scattering on a 100 au scale.

Accepted by ApJ

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Cited by in corpus (10)

• Constraining the Infalling Envelope Models of Embedded Protostars: BHR 71 and its Hot Corino
• The JCMT BISTRO survey: alignment between outflows and magnetic fields in dense cores/clumps
• A Pseudodisk Threaded with a Toroidal and Pinched Poloidal Magnetic Field Morphology in the HH 211 Protostellar System
• The Interplay between Ambipolar Diffusion and Hall Effect on Magnetic Field Decoupling and Protostellar Disc Formation
• An observational correlation between magnetic field, angular momentum and fragmentation in the envelopes of Class 0 protostars?
• Models of Rotating Infall for the B335 Protostar
• Constraining the magnetic field properties of Bok globule B335 using SOFIA/HAWC+
• Transition from ordered pinched to warped magnetic field on a 100 au scale in the Class 0 protostar B335
• Magnetic fields and outflows in the large Bok globule CB 54
• Synthetic Observations of the Infalling Rotating Envelope: Links between the Physical Structure and Observational Features