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34th Solar Physics Division Meeting, June 2003
Propagating Disturbances in the Lower Solar Corona
Meredith J. Wills-DaveySouthwest Research Institute
Boulder, [email protected]
34th Solar Physics Division Meeting, June 2003
Summary
Analysis of TRACE 13 June 1998 event
Wave profiles, flux
Evidence for spatial constraints on propagation?Implications of spatial constraints (“wave guides”)Conclusions
34th Solar Physics Division Meeting, June 2003
Wave fronts, trajectories can be automatically tracked, are complex
Thick black lines: measured wavefront positions at successive times
Thin black lines: interpolated wavefront positions
Thin white lines: natural propagation tracks between interpolated fronts
Thick white lines: tracks chosen for analysis
34th Solar Physics Division Meeting, June 2003
Cross-sections of density enhancement along tracks show
propagation
Time Density Enhanceme
nt
34th Solar Physics Division Meeting, June 2003
Wave kinetic energy flux does not match expectations for an impulsive
driver
Time
Total wave kinetic energy flux
34th Solar Physics Division Meeting, June 2003
Comparison of TRACE passbands suggests minimum altitude
34th Solar Physics Division Meeting, June 2003
Is there a maximum altitude? Evidence in theories and simulations
Original theoriesUchida (1968)Meyer (1968)
Meyer increasing Alfvén speed with altitude creates wave guidewave guideUchida shallower trajectories trapped in the atmosphere Uchida (1968)
34th Solar Physics Division Meeting, June 2003
Our simple model
Turnover in a stratified atmosphere
Terradas, Oliver, & Ballester (1999) finds trapping, analogous to turnover predicted by Meyer
Is there a maximum altitude? Evidence in theories and simulations
34th Solar Physics Division Meeting, June 2003
“Wave guiding” is consistent with current observations
EIT WavesUniformity of observationsDiscrepancy between propagating wave observations in EUV and soft x-ray corona
Courtesy of B. Thompson
34th Solar Physics Division Meeting, June 2003
ConclusionsPropagations are complex, reflecting complexity of the medium
Coronal Seismology?
Wave driver is non-impulsive, delivering energy over a period of minutes
CME as driver?
Propagations not consistent with spherical expansion, appear to be trapped in a coronal “wave guide”
34th Solar Physics Division Meeting, June 2003
A Surprising Find
Dispersion of the wave should relate to change in pulse width
No measurable width increaseResults consist with Results consist with dispersionless dispersionless conditionsconditions
Time
Pulse width
