Statistical Study of Coronal Mass Ejections of the 23rd and 24th Solar Cycles Based on Their Angular Width

Abstract

This study is based on the angular width of CMEs from the 23rd and 24th solar cycles. We divided the CMEs seen during the 23rd (1996–2007) and 24th (2008–2017) solar cycles into three categories: Narrow (width ≤ 20°), Intermediate (20° < width < 200°), and Wide (width ≥ 200°). It was found that the 24th solar cycle had twice as much as narrow CMEs than what occurred in the 23rd cycle. Similarly, there were about 1.2 times more intermediate CMEs in the 24th cycle than in the 23rd. Wide CMEs followed a similar trend of 1.3 times the number found for the 23rd cycle. Both cycles followed an analogous trend with respect to the number of CMEs based on their angular width. An intriguing find is that the percentage of slow (speed < 500 km/s) CMEs is greater in narrow and intermediate ones in the 23rd and 24th cycles compared to fast CMEs (speed > 500 km/s), whereas it is the opposite with wide CMEs. Wide CMEs are observed to have the highest mean speed among the three groups. Overall, it was found that all three groups of CMEs in the 23rd solar cycle had faster mean, median, maximum, and minimal speeds than those in the 24th cycle.