1. Magnetic fields in the infrared dark cloud G34.43+0.24
- Author
-
Archana Soam, Tie Liu, B-G Andersson, Chang Won Lee, Junhao Liu, Mika Juvela, Pak Shing Li, Paul F. Goldsmith, Qizhou Zhang, Patrick M. Koch, Kee-Tae Kim, Keping Qiu, Neal J. Evans II, Doug Johnstone, Mark Thompson, Derek Ward-Thompson, James Di Francesco, Ya-Wen Tang, Julien Montillaud, Gwanjeong Kim, Steve Mairs, Patricio Sanhueza, Shinyoung Kim, David Berry, Michael S. Gordon, Ken’ichi Tatematsu, Sheng-Yuan Liu, Kate Pattle, David Eden, Peregrine M. McGehee, Ke Wang, I. Ristorcelli, Sarah F. Graves, Dana Alina, Kevin M. Lacaille, Ludovic Montier, Geumsook Park, Woojin Kwon, Eun Jung Chung, Veli-Matti Pelkonen, Elisabetta R. Micelotta, Mika Saajasto, Gary Fuller, Department of Plant Biology [Carnegie] (DPB), Carnegie Institution for Science [Washington], Div Life Sci, Lab Proteome Anal & Mol Physiol, Gyeongsang Natl Univ, University of Helsinki, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Korea Astronomy and Space Science Institute (KASI), Okayama University, Fluids Laboratory for Aeronautical and Industrial Research, Department of Mechanical Engineering (FLAIR), Fluids Laboratory for Aeronautical and Industrial Research, National Research Council of Canada (NRC), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Moss Landing Marine Laboratories, Marine Chemical Research Institute - State Key Laboratory of Marine Paint, China Haohua Chemical Group Co., Centre d'étude spatiale des rayonnements (CESR), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Helsinki], Falculty of Science [Helsinki], University of Helsinki-University of Helsinki, King‘s College London, Department of Physics, and Particle Physics and Astrophysics
- Subjects
POLARIZATION ,010504 meteorology & atmospheric sciences ,Field (physics) ,FOS: Physical sciences ,Field strength ,F500 ,Astrophysics ,01 natural sciences ,114 Physical sciences ,STAR-FORMATION ,Protein filament ,0103 physical sciences ,Perpendicular ,SCUBA-2 ,Infrared dark cloud ,010303 astronomy & astrophysics ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Physics ,PRECURSORS ,Velocity dispersion ,Astronomy and Astrophysics ,115 Astronomy, Space science ,Astrophysics - Astrophysics of Galaxies ,Magnetic field ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,ISM: magnetic fields ,Magnetohydrodynamics ,MOLECULAR OUTFLOWS ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
We present the B-fields mapped in IRDC G34.43+0.24 using 850\,$\mu$m polarized dust emission observed with the POL-2 instrument at JCMT. We examine the magnetic field geometries and strengths in the northern, central, and southern regions of the filament. The overall field geometry is ordered and aligned closely perpendicular to the filament's main axis, particularly in regions containing the central clumps MM1 and MM2, whereas MM3 in the north has field orientations aligned with its major axis. The overall field orientations are uniform at large (POL-2 at 14$\arcsec$ and SHARP at 10$\arcsec$) to small scales (TADPOL at 2.5$\arcsec$ and SMA at 1.5$\arcsec$) in the MM1 and MM2 regions. SHARP/CSO observations in MM3 at 350\,$\mu$m from Tang et al. show a similar trend as seen in our POL-2 observations. TADPOL observations demonstrate a well-defined field geometry in MM1/MM2 consistent with MHD simulations of accreting filaments. We obtained a plane-of-sky magnetic field strength of 470$\pm$190\,$\mu$G, 100$\pm$40\,$\mu$G, and 60$\pm$34\,$\mu$G in the central, northern and southern regions of G34, respectively, using the updated Davis-Chandrasekhar-Fermi relation. The estimated value of field strength, combined with column density and velocity dispersion values available in the literature, suggests G34 to be marginally critical with criticality parameter $\rm \lambda$ values 0.8$\pm$0.4, 1.1$\pm$0.8, and 0.9$\pm$0.5 in the central, northern, and southern regions, respectively. The turbulent motions in G34 are sub-Alfv\'{e}nic with Alfv\'{e}nic Mach numbers of 0.34$\pm$0.13, 0.53$\pm$0.30, and 0.49$\pm$0.26 in the three regions. The observed aligned B-fields in G34.43+0.24 are consistent with theoretical models suggesting that B-fields play an important role in guiding the contraction of the cloud driven by gravity., Comment: 16 pages, 10 figures, Accepted for publication in ApJ
- Published
- 2019
- Full Text
- View/download PDF