On the Complex Magnetic Topology of Coronal Mass Ejections: An Enhanced Paradigm

The prevailing view of coronal mass ejections (CMEs) has long been that their magnetic field structure is best described by a highly twisted, circular cross-section magnetic flux rope model. This concept, which emerged from studies in the 1970s and 1980s, has become the foundation for most common CME depictions and has inspired various fitting models developed in the 1990s and 2000s. These models aim to provide three-dimensional visualizations of data from remote sensing and in situ measurements.

However, the landscape of CME research has evolved significantly since this paradigm's inception. A wealth of new data has emerged, including multi-point measurements, remote heliospheric observations, advanced physical models, and sophisticated numerical simulations. Collectively, these advancements have revealed that while the traditional paradigm explains certain CME characteristics, it falls short in capturing the full complexity of magnetic field structures in many instances.

This work provides a comprehensive review of four decades of continuous observations and ongoing research since the introduction of the highly twisted circular cross-section flux rope model. It proposes a more nuanced and realistic representation that better reflects the true intricacy of magnetic ejecta within CMEs. It also propses a new method to visualizing and quantifying the magnetic confuguration through the extraction of the magnetic helicity of CMEs during their journey to 1 AU, utilizing 3-D magneto-hydrodynamical (MHD) simulations.