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

• Main Author: Leonard, Andrew
• Other Authors: Morgan, Huw ; Li, Xing
• Published: Aberystwyth University 2016
• Subjects: 523.7
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690622

The solar corona is a hot, magnetised plasma of which several important aspects remain poorly understood. The Atmospheric Imaging Assembly (AIA) provides very high resolution images of the Sun in several extreme ultraviolet channels. AIA offers a unique chance to improve our understanding of the corona - qualitatively through detailed viewing of dynamic events and quantitatively through density and temperature diagnostics. This thesis presents a new software tool to quickly estimate coronal characteristics using AIA data. The method creates high-resolution temperature and emission measure maps of the whole solar disk within minutes. A slower but more thorough version is also developed as a comparison, and complimentary to, the main method. Both methods are tested extensively on synthetic data calculated from known temperature distributions and are then applied to real data. A prototype method for fast estimation of coronal line-of-sight emission distribution is also presented. A broad study investigates the characteristics of various coronal regions. The results are compared to previous works and found to be consistent, although the combination of values produced by the two methods reveals material cooler than that found by other studies, particularly at coronal hole boundaries. Another investigation applies the fast method to two sets of flaring active regions. A weak correlation exists between the flare size and mean temperature of the region for a small number of flares in one set. In the other set each region’s temperature variability over time is compared to a non-flaring region’s. The flaring regions’ mean temperatures are found to vary more than the non-flaring region’s - significantly more in several cases. This gives confidence in using such diagnostics as part of a future flare prediction method. The fast temperature map method presented here offers a significant speed advantage over similar methods, whilst maintaining robust results. This allows the maximum exploitation of AIA’s fine spatial and temporal resolution for temperature and emission measure studies.