An Analytical Solution for "EIT Waves"

Authors: M.J. Wills-Davey, C.E. DeForest; J.O. Stenflo
Affiliation: Southwest Research Institute, Boulder, Colorado; Southwest Research Institute, and on leave from Institute of Astronomy, University of Zurich

We present an analytical MHD solution that resolves many of the incongruities between plane-wave theory and current observations of the coronal pulses called "EIT waves". EIT waves are strongly correlated with coronal mass ejections, so understanding them and their relationship to the CME release process is important for predictive models of CME geo-effectiveness. With this solution, we show:

• how the propagation velocity can be much slower than the expected local Alfven and fast-mode speeds; and
• how the wave is able to remain coherent over large propagation distances.

Additionally, we show how our solution may provide a mechanism for instigating loop oscillations, and why CMEs are an ideal wave instigator.