The Search for Additional Ultra-Weak Magnetic Field A-type Stars and discovery of the Evolving Chemical Abundance Distributions in Alhena

dc.contributor.authorHollett, Angelo
dc.contributor.departmentPhysics, Engineering Physics and Astronomy
dc.contributor.supervisorWade's University at Kingstonen
dc.description.abstractAmong intermediate mass stars, only the chemically peculiar Ap/Bp stars have been historically found to be magnetic, with magnetic field strengths of a few hundred up to over 10 thousand gauss. In recent literature, a small number of early A type stars exhibiting magnetic field strengths of order 1 G or less have been reported. These ‘ultra-weak’ field stars are separated from their Ap/Bp counterparts by a so-called ‘magnetic desert’. The physical processes that give rise to ultra-weak field magnetism are still debated in literature. This is largely an issue of sample size, as only 5 ultra-weak field stars are currently known to exist. In an effort to continue the search for additional ultra-weak field stars, we derive a sample of intermediate mass stars that display similar observable qualities as previously detected ultra-weak field stars. We present the results of an observing proposal to ESPaDOnS at CFHT of the A star o Pegasi and report a constraint on the presence of an ultra-weak magnetic field. An outstanding member of our sample is the Am star Alhena, within the magnetic desert. We attempt to reproduce results of a previous study of this star, and in doing so uncover new evidence for evolving abundance distributions on time scales of a few years. We believe that this is the first instance of such behaviour observed in an Am or Ap star.
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dc.titleThe Search for Additional Ultra-Weak Magnetic Field A-type Stars and discovery of the Evolving Chemical Abundance Distributions in Alhena
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