Magnetic field of a ring-like shape molecular cloud

TL;DR

This study investigates the magnetic field structure of the ring-like G111 molecular cloud using multi-wavelength polarization and velocity data, revealing the magnetic field's role in shaping the cloud through shock compression and external forces.

Contribution

It provides a comprehensive analysis of the magnetic field in G111, demonstrating its dynamic importance and the influence of shock compression, with foreground contamination correction and multi-tracer approach.

Findings

Magnetic field is coherently aligned but varies spatially.

Field appears shaped by shock compression from stellar feedback or supernovae.

Magnetic forces are significant in the cloud's morphology.

Abstract

We present a detailed study of the magnetic field structure in the G111 molecular cloud, a ring-like filamentary cloud within the NGC 7538 region. We utilized interstellar dust polarization from the Planck telescope to trace large-scale field orientations, starlight extinction polarization from the Kanata telescope to probe the cloud's magnetic field after foreground subtraction, and velocity gradients derived from CO isotopologues, observed with the IRAP 30m telescope, to examine dense regions. Our results reveal a coherent yet spatially varying magnetic field within G111. We correct the significant foreground dust contamination through careful subtraction. We observe a global alignment of the magnetic field with density structures suggesting that the field is dynamically important in shaping the cloud. The curved magnetic field along the dense regions, coinciding with mid-infrared emission in WISE data, indicates shock compression, likely driven by stellar feedback or supernova remnants. Our findings support a scenario where G111's morphology results from turbulent shock-driven compression. The interplay between magnetic fields and external forces is crucial in shaping and maintaining the structure of the molecular cloud. Future high-resolution observations will be essential to further constrain the magnetic field's role in cloud evolution.