# Flux Accretion and Coronal Mass Ejection Dynamics

## TL;DR

This paper investigates how magnetic reconnection influences the acceleration and dynamics of coronal mass ejections (CMEs), emphasizing a feedback process called reconnective instability that affects CME modeling and observable properties.

## Contribution

It introduces the concept of reconnective instability, highlighting the importance of magnetic reconnection effects in CME acceleration models, which were previously often neglected.

## Key findings

- Reconnection modifies the magnetic structure and forces on CMEs.
- Reconnection can increase the upward acceleration of CMEs.
- The feedback process acts as an instability affecting CME dynamics.

## Abstract

Coronal mass ejections (CMEs) are the primary drivers of severe space weather disturbances in the heliosphere. Models of CME dynamics have been proposed that do not fully include the effects of magnetic reconnection on the forces driving the ejection. Both observations and numerical modeling, however, suggest that reconnection likely plays a major role in most, if not all, fast CMEs. Here, we theoretically investigate the accretion of magnetic flux onto a rising ejection by reconnection involving the ejection's background field. This reconnection alters the magnetic structure of the ejection and its environment, thereby modifying the forces acting upon the ejection, generically increasing its upward acceleration. The modified forces, in turn, can more strongly drive the reconnection. This feedback process acts, effectively, as an instability, which we refer to as a reconnective instability. Our analysis implies that CME models that neglect the effects of reconnection cannot accurately describe observed CME dynamics. Our ultimate aim is to understand changes in CME acceleration in terms of observable properties of magnetic reconnection, such as the amount of reconnected flux. This flux can be estimated from observations of flare ribbons and photospheric magnetic fields.