Discovery of Spatial Periodicities in a Coronal Loop Using Automated Edge-tracking Algorithms

A new method for automated coronal loop tracking, in both spatial and temporal domains, is presented. Applying this technique to trace data, obtained using the 171Å filter on 1998 July 14, we detect a coronal loop undergoing a 270 s kink-mode oscillation, as previously found by Aschwanden et al. (1999). However, we also detect flare-induced, and previously unnoticed, spatial periodicities on a scale of 3500 km, which occur along the coronal-loop edge. Furthermore, we establish a reduction in oscillatory power for these spatial periodicities of 45% over a 222 s interval. We relate the reduction in detected oscillatory power to the physical damping of these loop-top oscillations. Subject headings: Methods: data analysis — Techniques: image processing — Sun: corona — Sun: evolution — Sun: oscillations