Probing the Magnetic Fields and Dust Properties in the Young Embedded Star-forming Region AFGL 6366S Using Near-infrared and Optical Linear Polarimetry*

Abstract We present near-infrared (NIR) and optical linear polarimetry toward the partially embedded cluster AFGL 6366S. The polarization ranges from 0.44% to 10.3% in NIR and from 0.16% to 11.22% in the optical bands. The position angle spans 1°−179° in both the NIR and optical bands. About 22 stars exhibit intrinsic polarization signatures. A polarization hole is evident toward the densest (∼3.4 × 10 23 cm −2 ) and warmest (∼28.8 K) central cluster region. It is attributable to depolarization induced by radiative torque disruption of large grains and a modest contribution from magnetic field tangling. The local magnetic field toward the cluster’s central region is significantly misaligned with both the large-scale Galactic field and the long axis of the filament present in the region. The field morphology wraps around two dense molecular clumps with radii 0.34 and 0.22 pc and N (H 2 ) = (7.9 ± 1.1) × 10 22 cm −2 and (4.3 ± 0.5) × 10 22 cm −2 , respectively. The clumps are embedded in the filamentary structure and represent locally accelerated stages of mass accumulation. Gravitationally driven mass flows, largely perpendicular to the local magnetic field, produce a U-shaped field curvature across the filament axis. The plane-of-sky magnetic field strengths toward the two clumps are 447.91 ± 83.81 μ G and 396.66 ± 73.64 μ G. The corresponding mass-to-flux ratios ( λ ∼ 1.34 and 0.82) indicate that one clump is magnetically supercritical and the other is subcritical. The Alfvén Mach numbers M A ∼ 0.395 and 0.393 indicate that both clumps are in the sub-Alfvénic state.