Could bow-shaped magnetic morphologies surround filamentary molecular clouds? The 3D magnetic field structure of Orion-A
Journal article, 2019

Context. A new method based on Faraday rotation measurements recently found the line-of-sight component of magnetic fields in Orion-A and showed that their direction changes from the eastern side of this filamentary structure to its western side. Three possible magnetic field morphologies that can explain this reversal across the Orion-A region are toroidal, helical, and bow-shaped morphologies. Aims. In this paper, we constructed simple models to represent these three morphologies and compared them with the available observational data to find the most probable morphology(ies). Methods. We compared the observations with the models and used probability values and a Monte Carlo analysis to determine the most likely magnetic field morphology among these three morphologies. Results. We found that the bow morphology had the highest probability values, and that our Monte-Carlo analysis suggested that the bow morphology was more likely. Conclusions. We suggest that the bow morphology is the most likely and the most natural of the three morphologies that could explain a magnetic field reversal across the Orion-A filamentary structure (i.e., bow, helical and toroidal morphologies).

ISM: magnetic fields

stars: formation

ISM: clouds

magnetic fields


M. Tahani

University of Calgary

National Research Council Canada

R. Plume

University of Calgary

J. C. Brown

University of Calgary

J. D. Soler

Max Planck Society

Jouni Kainulainen

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 632 A68

Subject Categories

Astronomy, Astrophysics and Cosmology


Fusion, Plasma and Space Physics



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