Analysis of Slow and Fast Coronal Mass Ejections (CMEs) Across Solar Cycles 23 and 24

This study examines the characteristics of slow and fast Coronal Mass Ejections (CMEs) across solar cycles 23 and 24, focusing on variability in parameters such as speed, angular width, and kinetic energy and mass. Solar cycle 23, characterized by stronger solar activity, showed more variability in fast CMEs, particularly in parameters like angular width. This variability is potentially influenced by a power-law distribution in CME angular width, consistent with previous findings that indicate different expansion behaviors for slow and fast CMEs. This distribution suggests that expansion with propagation may contribute to the variability observed. Notably, slow CMEs showed early-cycle spikes in kinetic energy, while fast CMEs had energy peaks later in each cycle. The study also finds that CME speeds at 20 solar radii (20Rsun) are generally close to their linear speeds, with slight increases in variability for fast CMEs in cycle 24. Fast CMEs also demonstrate a stronger correlation with solar activity metrics across both cycles, indicating greater sensitivity to fluctuations in magnetic field and coronal conditions, especially with hemispheric activity levels. In contrast, slow CMEs exhibit greater variability between the cycles but are less correlated with solar activity, suggesting a stronger influence of internal CME dynamics. These findings emphasize the need for tailored CME propagation models, particularly for weaker solar cycles like cycle 24, where fast CMEs exhibit unique variability patterns. These findings emphasize the need for tailored CME propagation models for weaker solar cycles like cycle 24, where fast CMEs exhibit unique variability patterns.