CONTROL ID: 1683875
Twisting and Writhing with George Ellery Hale
Richard C Canfield
Department of Physics, Montana State University, Bozeman

Early in his productive career in astronomy, George Ellery Hale developed innovative instrumentation that allowed him to image the magnetically-dominated solar chromosphere.  Among the solar phenomena he discovered were sunspot vortices, which he attributed to storms akin to cyclones in our own atmosphere.  Much more recently, physicists discovered a quantity that is very well conserved in ideal magnetohydrodynamics: magnetic helicity.  Our contemporary understanding of Hale's vortices as a consequence of large-scale twist in sunspot magnetic fields hinges on this conservation.  I will review the crucial role that this property plays in the hemispheric and solar cycle dependences of Hales vortices, as well as solar flares and CMEs.