Distortion of Magnetic Fields in a Starless Core. V. Near-infrared and Submillimeter Polarization in FeSt 1-457
Kandori, Ryo; Nagata, Tetsuya; Tazaki, Ryo; Tamura, Motohide; Saito, Masao; Tomisaka, Kohji; Matsumoto, Tomoaki; Kusakabe, Nobuhiko; Nakajima, Yasushi; Kwon, Jungmi; Nagayama, Takahiro; Tatematsu, Ken’ichi
The relationship between submillimeter dust emission polarization and near-infrared (NIR) H-band polarization produced by dust dichroic extinction was studied for the cold starless dense core FeSt 1-457. The distributions of polarization angles (90°-rotated for the submillimeter) and degrees were found to be very different between submillimeter and NIR wavelengths. The mean polarization angles for FeSt 1-457 at submillimeter and NIR wavelengths are 132.°1 ± 22.°0 and 2.°7 ± 16.°2, respectively. The correlation between P H and A V was found to be linear from the outermost regions to the relatively dense lines of sight of A V ≈ 25 mag, indicating that NIR polarization reflects the overall polarization (magnetic field) structure of the core, at least in this density range. The flat P H /A V versus A V correlations were confirmed, and the polarization efficiency was found to be comparable to the observational upper limit. On the other hand, as reported by Alves et al. submillimeter polarization degrees show a clear linearly decreasing trend against A V from A V ≈ 20 mag to the densest center (A V ≈ 41 mag), appearing as a “polarization hole” structure. The power-law index for the P submm versus A V relationship was obtained to be ≈-1, indicating that the alignment for the submillimeter-sensitive dust is lost. These very different polarization distributions at submillimeter and NIR wavelengths suggest either that (1) there are different radiation environments at these wavelengths or (2) submillimeter-sensitive dust is localized or (3) a combination of both.