The Occurrence and Speed of CMEs Related to Two Characteristic Evolution Patterns of Helicity Injection in Their Solar Source Regions

TL;DR

This study analyzes the relationship between magnetic helicity injection patterns in solar active regions and the occurrence, speed, and characteristics of CMEs, revealing two distinct groups with different pre-CME conditions and behaviors.

Contribution

It identifies two characteristic helicity injection patterns that categorize CMEs and links these patterns to CME speed and associated flare properties, offering new insights into CME prediction.

Findings

Two helicity injection patterns correlate with CME groups.

CME speed is strongly correlated with helicity injection rate.

Different CME characteristics are linked to distinct helicity evolution patterns.

Abstract

Long-term (a few days) variation of magnetic helicity injection was calculated for 28 solar active regions which produced 47 CMEs to find its relationships with the CME occurrence and speed using SOHO/MDI line-of-sight magnetograms. As a result, we found that the 47 CMEs can be categorized into two different groups by two characteristic evolution patterns of helicity injection in their source active regions which appeared for about 0.5-4.5 days before their occurrence: (1) a monotonically increasing pattern with one sign of helicity (Group A; 30 CMEs in 23 active regions) and (2) a pattern of significant helicity injection followed by its sign reversal (Group B; 17 CMEs in 5 active regions). We also found that CME speed has a correlation with average helicity injection rate with linear correlation coefficients of 0.85 and 0.63 for Group A and Group B, respectively. In addition, these two CME groups show different characteristics as follows: (1) the average CME speed of Group B (1330km/s) is much faster than that of Group A (870km/s), (2) the CMEs in Group A tend to be single events, whereas those in Group B mainly consist of successive events, and (3) flares related to the CMEs in Group B are relatively more energetic and impulsive than those in Group A. Our findings therefore suggest that the two CME groups have different pre-CME conditions in their source active regions and different CME characteristics.