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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 742510.0, MPI für Astronomie / Publikationen_mpia
The JCMT BISTRO survey: The magnetic field strength in the Orion A filament
Authors:Pattle, K.; Ward-Thompson, D.; Berry, D.; Hatchell, J.; Chen, H.-R.; Pon, A.; Koch, P. M.; Kwon, W.; Kim, J.; Bastien, P.; Cho, J.; Coudé, S.; Di Francesco, J.; Fuller, G.; Furuya, R. S.; Graves, S. F.; Johnstone, D.; Kirk, J.; Kwon, J.; Lee, C. W.; Matthews, B. C.; Mottram, J. C.; Parsons, H.; Sadavoy, S.; Shinnaga, H.; Soam, A.; Hasegawa, T.; Lai, S.-P.; Qiu, K.; Friberg, P.
Date of Publication (YYYY-MM-DD):2017
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 122 (21 pp)
Audience:Not Specified
Abstract / Description:We determine the magnetic field strength in the OMC 1 region of the Orion A filament via a new implementation of the Chandrasekhar–Fermi method using observations performed as part of the James Clerk Maxwell Telescope (JCMT) B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. We combine BISTRO data with archival SCUBA-2 and HARP observations to find a plane-of-sky magnetic field strength in OMC 1 of {B}{pos}=6.6+/- 4.7 mG, where δ {B}{pos}=4.7 mG represents a predominantly systematic uncertainty. We develop a new method for measuring angular dispersion, analogous to unsharp masking. We find a magnetic energy density of ∼ 1.7× {10}-7 J m‑3 in OMC 1, comparable both to the gravitational potential energy density of OMC 1 (∼10‑7 J m‑3) and to the energy density in the Orion BN/KL outflow (∼10‑7 J m‑3). We find that neither the Alfvén velocity in OMC 1 nor the velocity of the super-Alfvénic outflow ejecta is sufficiently large for the BN/KL outflow to have caused large-scale distortion of the local magnetic field in the ∼500 yr lifetime of the outflow. Hence, we propose that the hourglass field morphology in OMC 1 is caused by the distortion of a primordial cylindrically symmetric magnetic field by the gravitational fragmentation of the filament and/or the gravitational interaction of the BN/KL and S clumps. We find that OMC 1 is currently in or near magnetically supported equilibrium, and that the current large-scale morphology of the BN/KL outflow is regulated by the geometry of the magnetic field in OMC 1, and not vice versa.
Free Keywords:ISM: individual objects: OMC 1; magnetic fields; techniques: polarimetric; stars: formation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.3847/1538-4357/aa80e5
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