Direct First PSP Observation of the Interaction of Two Successive Interplanetary Coronal Mass Ejections in November 2020

TL;DR

This study presents the first direct observation of the interaction between two successive interplanetary coronal mass ejections (ICMEs) by the Parker Solar Probe, revealing their internal magnetic evolution and collision effects during Solar Cycle 25.

Contribution

It introduces a comprehensive analysis combining multispacecraft data, remote sensing, and advanced modeling to characterize ICME interactions and internal magnetic structure evolution.

Findings

The two ICMEs interacted near PSP, affecting their magnetic structures.

Expansion and aging effects significantly influence ICME magnetic configurations.

The study demonstrates the importance of multi-technique approaches for ICME analysis.

Abstract

We investigate the effects of the evolutionary processes in the internal magnetic structure of two interplanetary coronal mass ejections (ICMEs) detected in situ between 2020 November 29 and December 1 by Parker Solar Probe (PSP). The sources of the ICMEs were observed remotely at the Sun in EUV and subsequently tracked to their coronal counterparts in white light. This period is of particular interest to the community since it has been identified as the first widespread solar energetic particle event of Solar Cycle 25. The distribution of various solar and heliospheric-dedicated spacecraft throughout the inner heliosphere during PSP observations of these large-scale magnetic structures enables a comprehensive analysis of the internal evolution and topology of such structures. By assembling different models and techniques, we identify the signatures of interaction between the two consecutive ICMEs and the implications for their internal structure. We use multispacecraft observations in combination with a remote-sensing forward modeling technique, numerical propagation models, and in-situ reconstruction techniques. The outcome, from the full reconciliations, demonstrates that the two CMEs are interacting in the vicinity of PSP. Thus, we identify the in-situ observations based on the physical processes that are associated with the interaction and collision of both CMEs. We also expand the flux rope modeling and in-situ reconstruction technique to incorporate the aging and expansion effects in a distorted internal magnetic structure and explore the implications of both effects in the magnetic configuration of the ICMEs.