Is there a Dynamic Difference between Stealthy and Standard CMEs?

TL;DR

This study compares the dynamic behaviors of stealthy and standard CMEs, revealing differences in the influence of forces like drag and Lorentz on their evolution, which enhances understanding of their mechanisms and potential geomagnetic impacts.

Contribution

It introduces a two-dimensional speed distribution analysis and force comparison between stealthy and standard CMEs, providing new insights into their driving mechanisms.

Findings

Both CME types are driven by combined forces in the inner corona.

Drag and gravitational forces are comparable to Lorentz force.

Stealthy CMEs are less affected by drag and Lorentz forces than standard CMEs.

Abstract

Stealthy Coronal Mass Ejections (CMEs), lacking low coronal signatures, may result in significant geomagnetic storms. However, the mechanism of stealthy CMEs is still highly debated. In this work, we investigate whether there are differences between the stealthy and standard CMEs in terms of their dynamic behaviors. Seven stealthy and eight standard CMEs with slow speeds are selected. We calculate two-dimensional speed distributions of CMEs based on the cross-correlation method, rather than the unidimensional speed, and further obtain more accurate distributions and evolution of CME mechanical energies. Then we derive the CME driving powers and correlate them with CME parameters (total mass, average speed, and acceleration) for standard and stealthy CMEs. Besides, we study the forces that drive CMEs, namely, the Lorentz force, gravitational force, and drag force due to the ambient solar wind near the Sun. The results reveal that both the standard and stealthy CMEs are propelled by the combined action of those forces in the inner corona. The drag force and gravitational force are comparable with the Lorentz force. However, the impact of the drag and Lorentz forces on the global evolution of the stealthy CMEs is significantly weaker than that of the standard CMEs.