# The causes of quasi-homologous CMEs

## TL;DR

This study investigates the origins of quasi-homologous CMEs, revealing different physical mechanisms and time scales for CMEs from the same or different source locations within active regions.

## Contribution

It identifies the magnetic source locations of 142 QH CMEs and proposes distinct mechanisms for S-type and D-type CMEs based on magnetic modeling and timing analysis.

## Key findings

- 63% of CMEs are S-type, originating from the same source as their predecessor.
- D-type CMEs have shorter waiting times, around 1.5 hours.
- Different physical mechanisms likely drive S-type and D-type CMEs.

## Abstract

In this paper, we identified the magnetic source locations of 142 quasi- homologous (QH) coronal mass ejections (CMEs), of which 121 are from solar cycle (SC) 23 and 21 from SC 24. Among those CMEs, 63% originated from the same source location as their predecessor (defined as S-type), while 37% origi- nated from a different location within the same active region as their predecessor (defined as D-type). Their distinctly different waiting time distribution, peaking around 7.5 and 1.5 hours for S- and D-type CMEs, suggests that they might involve different physical mechanisms with different characteristic time scales. Through detailed analysis based on non-linear force free (NLFF) coronal mag- netic field modeling of two exemplary cases, we propose that the S-type QH CMES might involve a recurring energy release process from the same source location (by magnetic free energy replenishment), whereas the D-type QH CMEs can happen when a flux tube system disturbed by a nearby CME.