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D.P. Clemens, K.E. Kraemer (Institute for Astrophysical Research, Boston University)
We have used the Infrared Space Observatory (ISO) to performed far-infrared polarimetry of the thermal dust emission toward the filamentary dark cloud GF9 (L1082) using the ISOPHOT instrument at a wavelength of 160 \mum. A star-forming dense core (centered on the IRAS source PSC 20503+6006), a starless dense core contained in filamentary material, and two reference positions were observed using the C200 2x2 pixel camera to test for the presence of embedded magnetic fields within the GF-9 filamentary cloud. The observations took the form of small, overlapping raster maps wherein each central sky position was viewed by each of the C200 pixels to allow accurate removal of instrumental polarization. The resulting 3x3 excess polarization maps of the core, the filament, and one reference region all show significantly detected far-infrared polarization, with polarization percentages typically around 2-12%. Of the three regions, the star-forming core shows the highest degree of magnetic field alignment (the smallest polarization position angle dispersion), indicating that the magnetic field is highly quiescent there. We find no evidence of any polarization ``hole'' toward the IRAS source, as can often be seen toward more massive embedded sources. The filament region exhibits strong changes in magnetic field direction, possibly signifying a highly disordered magnetic field supporting that dense core against collapse.
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