Temperature and emission diagnostics of the solar corona: mapping plasma characteristics using multi-channel Extreme UltraViolet observations

摘要

The solar corona is a hot, magnetised plasma of which several important aspectsudremain poorly understood. The Atmospheric Imaging Assembly (AIA) providesudvery high resolution images of the Sun in several extreme ultraviolet channels. AIAudoffers a unique chance to improve our understanding of the corona - qualitativelyudthrough detailed viewing of dynamic events and quantitatively through density andudtemperature diagnostics.udThis thesis presents a new software tool to quickly estimate coronal characteristicsudusing AIA data. The method creates high-resolution temperature and emissionudmeasure maps of the whole solar disk within minutes. A slower but more thoroughudversion is also developed as a comparison, and complimentary to, the main method.udBoth methods are tested extensively on synthetic data calculated from known temperatureuddistributions and are then applied to real data. A prototype method forudfast estimation of coronal line-of-sight emission distribution is also presented. Audbroad study investigates the characteristics of various coronal regions. The resultsudare compared to previous works and found to be consistent, although the combinationudof values produced by the two methods reveals material cooler than that foundudby other studies, particularly at coronal hole boundaries. Another investigation appliesudthe fast method to two sets of flaring active regions. A weak correlation existsudbetween the flare size and mean temperature of the region for a small number ofudflares in one set. In the other set each region?s temperature variability over timeudis compared to a non-flaring region?s. The flaring regions? mean temperatures areudfound to vary more than the non-flaring region?s - significantly more in several cases.udThis gives confidence in using such diagnostics as part of a future flare predictionudmethod. The fast temperature map method presented here offers a significant speedudadvantage over similar methods, whilst maintaining robust results. This allows theudmaximum exploitation of AIA?s fine spatial and temporal resolution for temperatureudand emission measure studies.