Early Evolution of Earth-Directed Coronal Mass Ejections in the Vicinity of Coronal Holes

Abstract

We investigate the deflection and rotation behaviour of 49 Earth-directed coronal mass ejections (CMEs) spanning the period from 2010 to 2020 aiming to understand the potential influence of coronal holes (CHs) on their trajectories. Our analysis incorporates data from coronagraphic observations captured from multiple vantage points, as well as extreme ultraviolet (EUV) observations utilised to identify associated coronal signatures such as solar flares and filament eruptions. For each CME, we perform a 3D reconstruction using the Graduated Cylindrical Shell (GCS) model. We perform the GCS reconstruction in multiple time steps, from the time at which the CME enters the field of view (FOV) of the coronagraphs to the time it exits. We analyse the difference in the longitude, latitude, and inclination between the first and last GCS reconstructions as possible signatures of deflection/rotation. Furthermore, we examine the presence of nearby CHs at the time of eruption and employ the Collection of Analysis Tools for Coronal Holes (CATCH) to estimate relevant CH parameters, including magnetic-field strength, centre of mass, and area. To assess the potential influence of CHs on the deflection and rotation of CMEs, we calculate the Coronal Hole Influence Parameter (CHIP) for each event and analyse its relationship with their trajectories. A statistically significant difference is observed between CHIP force and the overall change in a CME’s direction in the lower corona. The overall change in a CME’s direction accounts cumulatively for the change in latitude, longitude, and rotation. This suggests that the CHIP force in the low corona has a significant influence on the overall change in the direction of Earth-directed CMEs. However, as the CME evolves outward, the CHIP force becomes less effective in causing deflection or rotation at greater distances. Additionally, we observe a negative correlation between the deflection rate of the CMEs and their velocity, suggesting that higher velocities are associated with lower deflection rates. Hence, the velocity of a CME, along with the magnetic field from CHs, appears to play a significant role in the deflection of CMEs. By conducting this comprehensive analysis, we aim to enhance our understanding of the complex interplay between CHs, CME trajectories, and relevant factors such as velocity and magnetic-field strength.