Using extreme ultra-violet and soft x-ray observations as probes of magnetic reconnection during solar flares

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Montana State University - Bozeman, College of Letters & Science


Sunward-flowing voids above post-coronal mass ejection (CME) flare arcades were first discovered using the soft X-ray telescope (SXT) aboard Yohkoh and have since been observed with TRACE (extreme ultra-violet (EUV)), SOHO/LASCO (white light), SOHO/SUMER (EUV spectra), and Hinode/XRT (soft X-rays (SXR)). These supra-arcade downflows (SADs) have been shown to be plasma deficient with respect to their surroundings and follow trajectories which slow as they reach the top of the arcade. Characteristics such as these are consistent with post-reconnection magnetic flux tube cross-sections. The tubes retract from a reconnection site high in the corona until they reach a more potential magnetic configuration - a process in line with the standard model of reconnection. Viewed from a perpendicular angle, SADs should appear as shrinking loops rather than downflowing voids. In fact, observations of supra-arcade downflowing loops (SADLs) yield speeds and decelerations consistent with those determined for SADs. For this dissertation I have compiled a substantial SADs flare catalog and have developed semi-automatic detection software to detect and track individual downflows in order to provide statistically significant samples of parameters such as velocity, acceleration, area, magnetic flux, shrinkage energy, and reconnection rate. In addition, I provide measurements connecting supra-arcade upflows with flows observed by LASCO in the outer corona following a CME which further substantiates the standard reconnection model. I discuss these measurements, how they were obtained, and what impact they have on reconnection models.




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