Tuesday 16 Oct 2018: [Seminar] Stellar magnetism in the context of stellar evolution
Prof. Gregg Wade - RMC, Canada
IAIS Building/LT2 11:30-12:30
Stellar magnetic fields have essential impacts on the interior structure and bulk properties of stars at most evolutionary phases, modifying interior fluid flows, changing internal rotational profiles and distributions of nucleosynthetic chemicals, channeling and modifying outflowing winds, and slowing surface rotation through magnetic braking. Ultimately, these effects result in important changes to the evolution of stars, leading in particular to significant modifications of the relationships between stellar temperatures, luminosities, sizes and ages. They also influence the important outputs of stars in terms of the mass and luminous energy injected into the interstellar medium during their lives. More remarkably, they can also modify stellar end-states and influence the dramatic supernova explosions that mark the deaths of the most massive stars. These effects directly impact the properties of white dwarfs and neutron stars, and affect how populations of stars contribute to the structure and chemistry of their local galactic environments.
On the other hand, as stars age and evolve, so too do their magnetic fields. Hence we expect to observe important transformations of stellar magnetic fields as stars pass through various cycles of nuclear burning and undergo large changes to their temperatures, luminosities and sizes. As a consequence, the magnetic field of a star at one stage of its life may appear very different from that at a later stage. This is true not only for the observable magnetic fields expressed at stellar surfaces, but also for fields buried deep within internal convective and radiative zones.
In this talk I will describe our ongoing systematic exploration of the characteristics of magnetic fields of stars of various types spanning the HR diagram, with two principal applications: understanding quantitatively how magnetic fields influence stellar structure and evolution, and investigating how the observable magnetic fields of stars transform over stellar evolutionary timescales.