# A Pseudodisk Threaded with a Toroidal and Pinched Poloidal Magnetic Field Morphology in the HH 211 Protostellar System

## TL;DR

This study maps the magnetic field and kinematics of the youngest Class 0 protostellar system HH 211, revealing a pseudodisk with a highly pinched poloidal field and a significant toroidal component, providing insights into early disk formation.

## Contribution

It presents high-resolution polarization and kinematic observations of HH 211, demonstrating the magnetic field morphology and its role in pseudodisk formation with minimal magnetic braking evidence.

## Key findings

- Detected a flattened envelope extending to ~400 au with a misaligned rotating disk.
- Revealed a highly pinched poloidal magnetic field with a toroidal component.
- Found no significant magnetic braking, likely due to axis misalignment.

## Abstract

The HH 211 protostellar system is currently the youngest Class 0 system found with a rotating disk. We have mapped it at ~ 50 au (0.16") resolution, studying its magnetic field morphology with dust polarization in continuum at 232 and 358 GHz and its kinematics in C18O J=2-1 line. A flattened envelope extending out to ~ 400 au from the disk is detected in the continuum and C18O, slightly misaligned with the disk by 8 degree. It is spiraling inwards and expected to transform into a rotating disk at ~ 20 au, consistent with the disk radius estimated before. It appears to have a constant specific angular momentum and itself can result from an inside-out collapse of an extended envelope detected before in NH$_3$. In the flattened envelope, the polarization is mainly due to the magnetically aligned dust grains, inferring a highly pinched poloidal field morphology there. Thus, both the kinematics and field morphology support that the flattened envelope is a pseudodisk formed as the infalling gas is guided by the field lines to the equatorial plane. Interestingly, a point symmetric polarization distribution is also seen in the flattened envelope, implying that the pinched field lines also have a significant toroidal component generated by the rotation. No significant loss of angular momentum and thus no clear magnetic braking are detected in the flattened envelope around the disk probably because of the large misalignment between the axis of the rotation and the axis of the magnetic field in the cloud core.