The Large-Scale Structure of Magnetic Fields Associated with Filamentary Molecular Clouds

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dc.contributor.advisorPlume, René
dc.contributor.advisorBrown, Jo Anne C.
dc.contributor.authorTahani, Mehrnoosh
dc.contributor.committeememberHoude, Martin
dc.contributor.committeememberHobill, David W.
dc.contributor.committeememberKnudsen, David J.
dc.contributor.committeememberBehjat, Laleh
dc.date2019-06
dc.date.accessioned2019-01-24T17:56:31Z
dc.date.available2019-01-24T17:56:31Z
dc.date.issued2019-01-22
dc.description.abstractMagnetic fields pervade the interstellar medium and are believed to be important in the star formation process. However, probing magnetic fields in these star-forming regions is challenging. I propose and demonstrate a new method, using Faraday rotation measurements, to probe the direction and magnitude of the magnetic field along the line-of-sight in and around filamentary molecular clouds that are forming stars. Using my method, which utilises rotation measure data from the literature, a chemical evolution code, and extinction maps to estimate electron column density, I determine the magnetic field in four nearby molecular clouds: Orion A, Orion B, Perseus, and California. I find that my method produces results in agreement with the limited number of available Zeeman measurements. Using the magnetic field results from this new method, I find that the line-of-sight magnetic field on either side of the California and Orion A filaments has opposing magnetic field directions. Three theoretical magnetic field morphologies can explain this change of direction across filaments: toroidal, helical, and bow morphologies. I investigate these three models by combining my results with those of Planck observations to determine the 3D magnetic field structure in Orion A. I find that of the three possible morphologies, toroidal is the least probable whereas the bow morphology is the most natural. To investigate these morphologies further, I use magnetohydrodynamics simulations to simulate filamentary molecular clouds and their magnetic field evolution. I use different initial parameters to see if the magnetic field lines can become twisted around a rotating filament, potentially forming helical fields. I find that helical fields are not easily generated in these scenarios.en_US
dc.identifier.citationTahani, M. (2019). The Large-Scale Structure of Magnetic Fields Associated with Filamentary Molecular Clouds (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/35767
dc.identifier.urihttp://hdl.handle.net/1880/109508
dc.language.isoenen_US
dc.publisher.facultyScienceen_US
dc.publisher.institutionUniversity of Calgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.subjectStar Formation, Magnetism, Molecular Clouds, Faraday Rotation, Magnetohydrodynamicsen_US
dc.subject.classificationAstronomy and Astrophysicsen_US
dc.titleThe Large-Scale Structure of Magnetic Fields Associated with Filamentary Molecular Cloudsen_US
dc.typedoctoral thesisen_US
thesis.degree.disciplinePhysics & Astronomyen_US
thesis.degree.grantorUniversity of Calgaryen_US
thesis.degree.nameDoctor of Philosophy (PhD)en_US
ucalgary.item.requestcopytrue
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