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Colloquium Speaker: Matthew Shultz (University of Delaware)
March 10, 2021 @ 3:30 pm - 5:00 pm
Speaker: Matthew Shultz (University of Delaware)
Title: Magnetic Fields and Magnetospheres of Hot Stars
Abstract:
Dynamos should not exist within the radiative envelopes of early-type stars, making the existence of strong, stable magnetic fields in upper main sequence objects a mystery that has gone unsolved for over 70 years. These ‘fossil’ magnetic fields are believed to be remnants of a previous evolutionary stage, but while recent population studies have clarified their main-sequence evolution, the origin of fossil fields remains obscure. These powerful magnetic fields dominate their circumstellar environments, channelling supersonic radiation-driven winds into magnetospheres corotating out to tens of stellar radii, which are detectable across the electromagnetic spectrum. Hot star magnetospheres possess several advantages – stability, detectability, independent and precise magnetic and rotational constraints – that make them promising laboratories. The recent discovery that plasma transport is governed by centrifugally driven reconnection points the way to a unified framework that will enable multiwavelength analyses simultaneously probing several magnetospheric regions, thereby obtaining a holistic understanding of the behaviour of magnetized plasmas under extreme conditions.