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A new trigger mechanism for coronal mass ejections: the role of confined flares and photospheric motions in the formation of hot flux rope

Alexander James - European Space Astronomy Centre, Spain; Lucie Green - University College London, United Kingdom; Lidia van Driel-Gesztelyi - University College London, United Kingdom; Gherardo Valori - University College London, United Kingdom

Session: The Solar Sources of Space Weather

Abstract

Many previous studies have shown that the magnetic precursor of a coronal mass ejection (CME) takes the form of a magnetic flux rope, and a subset observed at plasma temperatures of ~10^7 K have become known as "hot flux ropes''. We seek to identify the processes by which these hot flux ropes form, with a view to developing our understanding of CMEs and thereby improving space weather forecasts. Extreme-ultraviolet observations were used to identify five pre-eruptive hot flux ropes in the solar corona, and the evolution of the photospheric magnetic field was studied over several days before they erupted to investigate how they formed. Evidenced by confined solar flares in the hours and days before the CMEs, we conclude the hot flux ropes formed via magnetic reconnection in the corona, contrasting many previously-studied flux ropes that formed lower down in the solar atmosphere via magnetic cancellations. This coronal reconnection is driven by observed “orbiting” motions of photospheric magnetic flux fragments around each other, which bring magnetic flux tubes together in the corona. This represents a novel trigger mechanism for solar eruptions, and should be considered when predicting solar magnetic activity.


Approaching deadlines:

Registration opens:

16 July 2020

Abstract submission opens:

16 July 2020

European Space Weather Medals:

6 September 2020

Registration deadline:

25 September 2020

Registration deadline: [extended]

10 October 2020

Abstract submission deadline:

4 September 2020