Magnetic Field Uniformity Across the GF 9-2 YSO, L1082C Dense Core, and GF 9 Filamentary Dark Cloud

Abstract

The orientation of the magnetic field ( B field) in the filamentary dark cloud GF 9 was traced from the periphery of the cloud into the L1082C dense core that contains the low-mass, low-luminosity Class 0 young stellar object (YSO) GF 9-2 (IRAS 20503+6006). This was done using SOFIA HAWC+ dust thermal emission polarimetry (TEP) at 216  μ m in combination with Mimir near-infrared background starlight polarimetry (BSP) conducted in the H band (1.6 μ m) and K band (2.2 μ m). These observations were augmented with published I -band (0.77 μ m) BSP and Planck 850  μ m TEP to probe B -field orientations with offset from the YSO in a range spanning 6000 au to 3 pc. No strong B -field orientation change with offset was found, indicating remarkable uniformity of the B -field from the cloud edge to the YSO environs. This finding disagrees with weak-field models of cloud core and YSO formation. The continuity of inferred B -field orientations for both TEP and BSP probes is strong evidence that both are sampling a common B field that uniformly threads the cloud, core, and YSO region. Bayesian analysis of Gaia  DR2 stars matched to the Mimir BSP stars finds a distance to GF 9 of 270 ± 10 pc. No strong wavelength dependence of B -field orientation angle was found, contrary to previous claims.