The Mystery of the Broken Field Line

Eric Donovan (University of Calgary)
Event Date and Time: 
Mon, 2012-01-30 16:00 - 17:00
Hennings 318
Local Contact: 
Jaymie Matthews
Intended Audience: 
The solar wind interacts with Earth’s magnetic field, creating our magnetosphere. Magnetospheric processes are interesting as exemplars of fundamental phenomena and because they affect our environment. For two fundamental knowledge examples, the Sun-Earth system is the only astrophysical object in which magnetic reconnection and its consequences can be directly observed, and geospace is a natural accelerator where low-energy electrons and protons are brought to very high energies. Energy captured from the solar wind supports global plasma convection within the magnetosphere, magnetospheric currents, and the wind-sock shaped magnetotail. The energy is dissipated via a number of processes including the aurora and heating of the upper atmosphere. When input outpaces dissipation, the magnetotail becomes increasingly stretched. It is a quirk of the system that the excess energy stored in the stretched magnetotail is released explosively (rather than gradually) in a sudden reconfiguration of the magnetic field topology. This cycle of storage, release, and recovery is called the magnetic substorm. The explosive release is called onset, and marks the beginning of a plasma instability that starts small and develops to have global effects, one of which is fantastic auroral displays (many of which are over Canada). What plasma instability is responsible for onset? This is one of the key unresolved questions in space physics. In this talk I will outline the two candidate solutions, focusing on how Canadian ground-based auroral imaging is playing a central role in the ongoing international effort towards closure of the question.
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