A Study on the Nested Rings CME Structure Observed by the WISPR Imager Onboard Parker Solar Probe

TL;DR

This paper analyzes a complex CME observed by Parker Solar Probe's WISPR imager, revealing nested rings that indicate the embedded helical magnetic flux rope structure, enhancing understanding of CME interior morphology.

Contribution

It introduces a detailed morphological analysis of a CME with nested rings, linking observed structures to the three-dimensional flux rope geometry, which is a novel insight.

Findings

Nested rings correspond to the flux rope structure.

Observation perspective influences substructure visibility.

The morphology reveals the magnetic field geometry.

Abstract

Despite the significance of coronal mass ejections (CMEs) in space weather, a comprehensive understanding of their interior morphology remains a scientific challenge, particularly with the advent of many state-of-the-art solar missions such as Parker Solar Probe (Parker) and Solar Orbiter (SO). In this study, we present an analysis of a complex CME as observed by the Wide-Field Imager for Solar PRobe (WISPR) heliospheric imager during Parker's seventh solar encounter. The CME morphology does not fully conform with the general three-part density structure, exhibiting a front and core not significantly bright, with a highly structured overall configuration. In particular, its morphology reveals non-concentric nested rings, which we argue are a signature of the embedded helical magnetic flux rope (MFR) of the CME. For that, we analyze the morphological and kinematical properties of the nested density structures and demonstrate that they outline the projection of the three-dimensional structure of the flux rope as it crosses the lines of sight of the WISPR imager, thereby revealing the magnetic field geometry. Comparison of observations from various viewpoints suggests that the CME substructures can be discerned owing to the ideal viewing perspective, close proximity, and spatial resolution of the observing instrument.