Circular polarimetry reveals helical magnetic fields in the young stellar object HH 135-136

TL;DR

This study uses circular polarimetry and modeling to demonstrate that the magnetic field in the HH 135-136 young stellar object is helical, supporting its role in outflow collimation and star formation.

Contribution

It provides the first imaging evidence of a helical magnetic field in a young stellar outflow, highlighting its importance in star formation processes.

Findings

Magnetic field along the outflow is helical.

The field maintains its shape over large distances.

Supports magnetic collimation of outflows.

Abstract

Magnetic fields are believed to have a vital role in regulating and shaping the flow of material onto and away from protostars during their initial mass accretion phase. It is becoming increasingly accepted that bipolar outflows are generated and collimated as material is driven along magnetic field lines and centrifugally accelerated off a rotating accretion disk. However, the precise role of the magnetic field is poorly understood and evidence for its shape and structure has not been forthcoming. Here we report imaging circular polarimetry in the near-infrared and Monte Carlo modelling showing that the magnetic field along the bipolar outflow of the HH 135-136 young stellar object is helical. The field retains this shape for large distances along the outflow, so the field structure can also provide the necessary magnetic pressure for collimation of the outflow. This result lends further weight to the hypothesis - central to any theory of star formation - that the outflow is an important instrument for the removal of high-angular-momentum material from the accretion disk, thereby allowing the central protostar to increase its mass.