Morphological and Kinematic Evolution of Three Interacting Coronal Mass Ejections of 2011 February 13-15

TL;DR

This study analyzes the evolution, interaction, and collision of three successive CMEs in 2011 using multi-viewpoint observations, revealing inelastic collision characteristics and implications for space weather prediction.

Contribution

It provides detailed analysis of CME interactions and collision dynamics using STEREO observations, highlighting the importance of HI data for space weather forecasting.

Findings

Evidence of CME-CME interaction and collision was observed.

The collision between CMEs was classified as inelastic, near elastic.

Post-collision, CMEs remained distinct and adjacent in the heliosphere.

Abstract

During 2011 February 13 to 15, three Earth-directed CMEs launched in successively were recorded as limb CMEs by coronagraphs (COR) of STEREO. These CMEs provided an opportunity to study their geometrical and kinematic evolution from multiple vantage points. In this paper, we examine the differences in geometrical evolution of slow and fast speed CMEs during their propagation in the heliosphere. We also study their interaction and collision using STEREO/SECCHI COR and Heliospheric Imager (HI) observations. We have found evidence of interaction and collision between the CMEs of February 15 and 14 in COR2 and HI1 FOV, respectively, while the CME of February 14 caught the CME of February 13 in HI2 FOV. By estimating the true mass of these CMEs and using their pre and post-collision dynamics, the momentum and energy exchange between them during collision phase are studied. We classify the nature of observed collision between CME of February 14 and 15 as inelastic, reaching close to elastic regime. Relating imaging observations with the in situ measurements, we find that the CMEs move adjacent to each other after their collision in the heliosphere and are recognized as distinct structures in in situ observations by WIND spacecraft at L1. Our results highlight the significance of HI observations in studying CME-CME collision for the purpose of improved space weather forecasting.