The JCMT BISTRO-3 Survey: Variation of magnetic field orientations on parsec and sub-parsec scales in the massive star-forming region G28.34+0.06

TL;DR

This study examines magnetic field orientations and strengths across different scales in a massive star-forming region, revealing a perpendicular change in orientation likely driven by gravitational collapse.

Contribution

It provides the first comparison of magnetic field orientations at parsec and sub-parsec scales in G28.34+0.06, highlighting the role of gravity in magnetic field evolution during star formation.

Findings

Magnetic fields are perpendicular between clump and core scales.

Magnetic field strengths range from 50 to 430 μG.

Mass-to-flux ratio indicates collapse is not fully supported by magnetic fields.

Abstract

Magnetic fields play a significant role in star-forming processes on core to clump scales. We investigate magnetic field orientations and strengths in the massive star-forming clump P2 within the filamentary infrared dark cloud G28.34+0.06 using dust polarization observations made using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope as part of the B-field In STar-forming Region Observations (BISTRO) survey. We compare the magnetic field orientations at the clump scale of ~2 parsecs from these JCMT observations with those at the core scale of ~0.2 parsecs from archival ALMA data, finding that the magnetic field orientations on these two different scales are perpendicular to one another. We estimate the distribution of magnetic field strengths, which range from 50 to 430 {\mu}G over the clump. The region forming the core shows the highest magnetic field strength. We also obtain the distribution of mass-to-flux ratios across the clump. In the region surrounding the core, the mass-to-flux ratio is larger than 1, which indicates the magnetic field strength is insufficient to support the region against gravitational collapse. Therefore, the change in the magnetic field orientation from clump to core scales may be the result of gravitational collapse, with the field being pulled inward along with the flow of material under gravity.