# Difference of source regions between fast and slow coronal mass ejections

## TL;DR

This study compares the source regions of fast and slow coronal mass ejections, revealing that fast CMEs originate from regions with rapidly changing magnetic field structures, unlike slow CMEs.

## Contribution

It provides a detailed analysis of the magnetic field structures in CME source regions, highlighting differences between fast and slow CMEs based on potential magnetic field calculations.

## Key findings

- Fast CMEs originate in regions with rapidly changing magnetic fields.
- Both types of eruptions have similar pre-eruptive magnetic energy levels.
- Magnetic field structure differences influence CME speed and behavior.

## Abstract

Coronal mass ejections (CMEs) are tightly related to filament eruptions and usually are their continuation in the upper solar corona. It is common practice to divide all observed CMEs into fast and slow ones. Fast CMEs usually follow eruptive events in active regions near big sunspot groups and associated with major solar flares. Slow CMEs are more related to eruptions of quiescent prominences located far from active regions. We analyze ten eruptive events with particular attention to the events on 2013 September 29 and on 2016 January 26, one of which was associated with a fast CME, while another was followed by a slow CME. We estimated the initial store of free magnetic energy in the two regions and show the resemblance of pre-eruptive situations. The difference of late behaviour of the two eruptive prominences is a consequence of the different structure of magnetic field above the filaments. We estimated this structure on the basis of potential magnetic field calculations. Analysis of other eight events confirmed that all fast CMEs originate in regions with rapidly changing with height value and direction of coronal magnetic field.