Abstract
On 13 June 1998 an “EIT wave” was observed by the TRACE satellite, initiated by a flare outside the TRACE field of view. This allowed for deep exposure observations, something rare with “EIT wave”. To study the wave dynamics we examine a time series of base difference images, taking slices radiating from the flare origin. Graphs of the slices show changes in intensity with respect to a pre-flare image. We find the “EIT wave” is observable as a propagating crest for 400–500 second before it dissipates and/or is disrupted by in-situ magnetic structures. We examine eight vectors that can be modelled in part by Gaussian curves. Velocities determined by measuring from peak intensities (the “center” of the wave rather than a visually determined wave front) give a wide range of values; the eastern portion of the wave front moves coherently at ∼350 km/s, while the western wave front slows dramatically and shows possible deflection. One of the slices appears to map ejecta, rather than a wave front trajectory. Initial results show that the “EIT wave” crests do not exhibit a monotonic dissipation, but instead seem to maintain or increase in size for hundreds of seconds before dimming and broadening. Similarly, the depleted region following each crest also becomes larger over time. The intensity increase may represent material heating into the TRACE 195passband, or it may be evidence of a soliton behavior. The large intensity decrease behind the wave front appears to be the coronal dimming often associated with coronal mass ejections.
Published Version
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