1 / 8

An Analytical Solution for “EIT Waves”

This study presents an analytical solution for EIT (Extreme Ultraviolet Imaging Telescope) waves, focusing on their observed properties and challenges in modeling. EIT waves are characterized by large, single-pulse fronts, intensity enhancements, and slow propagation speeds compared to Alfven waves. We propose a soliton solution that fits observed characteristics without the limitations of traditional plane wave models. This non-linear approach matches the observed velocities and density perturbations and has implications for coronal seismology and studies of large-scale solar events.

arty
Download Presentation

An Analytical Solution for “EIT Waves”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Analytical Solution for “EIT Waves” M. J. Wills-Davey, C. E. DeForest, Southwest Research Institute, Boulder, Colorado and J. O. Stenflo Southwest Research Institute (on leave from Institute of Astronomy, University of Zurich) meredith@boulder.swri.edu

  2. Observed Properties of “EIT Waves” • Large, single-pulse fronts • Intensity-enhancements (compressional MHD waves) • Travel global distances through QS • Tend to travel much more slowly than the Alfvén or fast-mode speeds (~300 km/s vs. ~600-1000 km/s) • Often instigate loop oscillations EIT Event: 12 May 1997 Image provided by B. J. Thompson

  3. TRACE Event: 13 June 1998

  4. Certain properties of EIT waves have been difficult to model. If you use plane waves, it’s hard to: • make ubiquitous waves move slowly. • create a long-lived, coherent single pulse. • Dispersion should show periodicity. • instigate loop oscillations with a plane wave.

  5. A Soliton Solution • Non-linear • Matches observations • Assume a simple MHD environment • No boundaries • v B Density: ρ = ρ0 + ρ1sech2[x-cwt/Lw] Solutions with constant cw, no dispersion are possible.

  6. [(1 – 3 )cs2 + (1 – 2 )vA2]2 ρ1 ρ0 ρ1 ρ0 ρ1 ρ0 ρ1 ρ0 (cs2 + vA2)[3( )2– 3 + 1) ρ1 ρ0 For the “EIT Wave Solution:” cw2 = • cw2 depends on the initial conditions. • For a range of ρ1/ρ0 01, cw2 < vA2 Waves travel at observed velocities and with consistent density perturbations.

  7. Instigating Loop Oscillations • Unlike plane waves, solitons do not return things to IC • Shifts about pulse width • Consistent with observations Solitons must generate loop displacement.

  8. Conclusion Solitons provide a simple, non-linear solution consistent with observations. • Relation to CMEs • Large events ideal non-linear wave generator • Better geometry, boundary conditions • Gravity, surface curvature, more-D propagation • Now may be useful for coronal seismology Where to go now…

More Related