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arXiv · 2410.15964

The magnetic topology of AR13664 leading to its first halo CME

David MacTaggart·Tom Williams·OPM Aslam
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Abstract

In the first half of May 2024, the solar active region (AR)13664 was responsible for generating the strongest geomagnetic storm in over 20 years, through an enhanced production of X-class flares and coronal mass ejections (CMEs). A key factor in this production was the complex magnetic topology of AR13664. In this work, we investigate the region's magnetic topology related to the production of its first halo CME on May 8th. This is achieved by combining different observations of magnetic topology based on photospheric magnetic winding signatures and nonlinear force-free extrapolations, together with Atmospheric Imaging Assembly (AIA) observations at different wavelengths. We present evidence that the first halo CME, and its associated X1 flare, was created by an emerging bipole of twisted magnetic field, following the general picture of the standard flare model. The coincidence of the first large magnetic winding signature with the start time of the X1 flare, provides the onset time for the CME as well as the period of enhanced eruptive activity of the region - 04:36UT on May 8th. Finally, our topological analysis identifies the key topological sub-regions of AR13664 that can lead to subsequent eruptions, which will be useful for further studies of this region.

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David MacTaggart, Tom Williams, OPM Aslam. 2024-10-21. The magnetic topology of AR13664 leading to its first halo CME. https://arxiv.org/abs/2410.15964

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