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arXiv · 2504.08996

Evidence of Extreme Ultraviolet Resonant Excitation in the Middle Corona During A Solar Flare

Daniel B. Seaton·Cooper Downs·Giulio Del Zanna·Matthew J. West·Edward M. B. Thiemann·Amir Caspi·Edward E. DeLuca·Leon Golub·James Paul Mason·Ritesh Patel·Katharine K. Reeves·Yeimy Rivera·Sabrina Savage
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Abstract

We present observations of an eruptive solar flare on 2016 January 6 that occurred behind the solar limb from the perspective of the Earth, but was well observed by STEREO and the Solar Extreme Ultraviolet Monitor on the Mars Atmosphere and {Volatile} EvolutioN (MAVEN) mission. Light curves showing the evolution of the flare's irradiance as a function of time taken by MAVEN are well correlated with the brightness evolution of fan structures observed in the PROBA2 SWAP 174 {\AA} passband, suggesting that the radiance of structures near the flare site was influenced by emission from the flare. Because SWAP did not directly observe the flare itself, this event represents a rare opportunity to study the evolution of emission near a flare without the risk of instrumental scattered light contaminating the observations. We analyze this evolution and implement a simple model to explore the possibility that resonant excitation (or resonant scattering) plays an important role in driving coronal EUV emission during flaring events. Our modeling shows that for a large flare, resonant excitation could increase emission from nearby structures by about 45%, consistent with our findings that the involved structures observed by SWAP increased in brightness by about 60% during the flare. We conclude that resonant excitation may play an important role in driving coronal EUV emission under certain circumstances and should be accounted for in models and emission-based analysis tools.

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Daniel B. Seaton, Cooper Downs, Giulio Del Zanna, Matthew J. West, Edward M. B. Thiemann, Amir Caspi, Edward E. DeLuca, Leon Golub, James Paul Mason, Ritesh Patel, Katharine K. Reeves, Yeimy Rivera, Sabrina Savage. 2025-04-11. Evidence of Extreme Ultraviolet Resonant Excitation in the Middle Corona During A Solar Flare. https://doi.org/10.3847/1538-4357%2Fadcab5

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