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dc.contributor.authorKeszthelyi, Zsolt
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date.accessioned2019-08-12T17:54:13Z
dc.date.available2019-08-12T17:54:13Z
dc.identifier.urihttp://hdl.handle.net/1974/26465
dc.description.abstractModels describing the evolution of massive stars have advanced significantly due to understanding and including key physical phenomena in the calculations, such as mass loss and rotation. As stellar magnetometry has progressed very rapidly in the past decade, recent efforts have begun to focus on characterizing magnetic properties of massive stars and including their effects in evolutionary model calculations. By implementing established scaling relations of surface fossil magnetic fields, we account for magnetic braking, mass-loss quenching, and time evolution; using a simple, coherent prescription. In our study, we use two well-known hydrodynamical stellar evolution codes: the Modules for Experiments in Stellar Astrophysics (MESA) software instrument and the Geneva stellar evolution code (GENEC). We show that the incorporation of the effects of surface fossil magnetic fields impacts the model predictions, and, as a consequence, implies that the previous analysis of observed magnetic massive stars, which utilized non-magnetic evolutionary models for comparison, may need to be revised. We reinforce that magnetic braking and rotational mixing produce stars that can be identified as Group~2 (slowly-rotating, nitrogen-enriched) stars on the Hunter diagram, and we place constraints on their observable magnetic field strengths. We identify a unique feature of initially fast-rotating magnetic stars: following their initial blueward evolution, their rapid spin-down leads to apparently similar evolutionary tracks as if the star initiated its evolution as a slow rotator. This can, amongst others, affect the age determination of magnetic massive stars. Metallicity affects the stellar mass-loss rates, which are reduced if the star is in a low-metallicity environment. We show that surface fossil magnetic fields can also greatly reduce the mass-loss rate of the star. Therefore, even in high-metallicity environments, magnetic massive stars may follow an evolutionary path that resembles that of stars in a low-metallicity environment. As a consequence, astrophysical phenomena that are canonically attributed to massive stars in distant galaxies could potentially be produced by magnetic progenitors in the Milky Way. We conclude that the inclusion of new physical ingredients advances state-of-the-art model predictions, and therefore these models provide a basis for a platform to further investigate the nature of magnetic massive stars.en_US
dc.language.isoenen_US
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectmassive staren_US
dc.subjectstellar evolutionen_US
dc.subjectfossil fieldsen_US
dc.subjectsurface magnetic fieldsen_US
dc.subjectmagnetic brakingen_US
dc.subjectmass-loss rateen_US
dc.titleThe role of surface fossil magnetic fields in massive star evolutionen_US
dc.typethesisen
dc.description.degreeDoctor of Philosophyen_US
dc.contributor.supervisorWade, Gregg
dc.contributor.departmentPhysics, Engineering Physics and Astronomyen_US


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