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M. J. Wills-Davey (Montana State University)
On 13 June 1998, an ``EIT wave'' was observed by the TRACE satellite, initiating from a flare outside the TRACE field of view. The absence of the flare allowed for deep exposure observations, something rare with ``EIT waves.'' To study intensity dynamics, we examine a time series of base difference images of the wave.
Previous studies of ``EIT waves'' have generally been done ``by eye,'' where a scientist determines the wave's propagation front based on visual inspection of difference images. To eliminate the ``human variable,'' we have automated this process, allowing the computer to find intensity maxima in space and time. The resulting propagation fronts differ remarkably from earlier visual wave front measurements, calling into question the validity of ``by eye'' techniques.
Using the new propagation fronts, we use interpolations and Huygens plotting techniques to determine the trajectories of points along the wave. These new trajectories show a great deal of buffeting, most likely due to variations in local magnetic fields. Intensity profiles along ten trajectories are examined, with vastly different results for the eastern and western sides of the front. We also consider the extension of the intensity front along a magnetic structure, which appears to be evidence of the wave being preferentially directed parallel to the local field.
This research was supported by an American Fellowship from the AAUW Educational Foundation and by a TRACE grant from NASA to Montana State University.
The author(s) of this abstract have provided an email address for comments about the abstract: meredith@solar.physics.montana.edu
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.