Velocity Distribution Associated With EUV Disturbances Caused by Eruptive MFR

Zhixing Mei,Yan Li,Jing Ye,Bojing Zhu,Qiangwei Cai

doi:10.3389/fspas.2021.771882

Abstract

Extreme ultraviolet (EUV) disturbances are ubiquitous during eruptive phenomena like solar flare and Coronal Mass Ejection (CME). In this work, we have performed a three-dimensional (3D) magnetohydrodynamic numerical simulation of CME with an analytic magnetic fluxrope (MFR) to study the complex velocity distribution associated with EUV disturbances. When the MFR erupts upward, a fast shock (FS) appears as a 3D dome, followed by outward moving plasma. In the center of the eruptive source region, an expanding CME bubble and a current sheet continuously grow, both of which are filled by inward moving plasma. At the flanks of the CME bubble, a complex velocity distribution forms because of the dynamical interaction between inward and outward plasma, leading to the formation of slow shock (SS) and velocity separatrix (VS). We note two types of vortices near the VS, not mentioned in the preceding EUV disturbance simulations. In first type of vortex, the plasma converges toward the vortex center, and in the second type, the plasma spreads out from the center. The forward modeling method has been used to create the synthetic SDO/AIA images, in which the eruptive MFR and the FS appear as bright structures. Furthermore, we also deduce the plasma velocity field by utilizing the Fourier local correlation tracking method on the synthetic images. However, we do not observe the VS, the SS, and the two types of vortices in this deduced velocity field.

Highlights

Coronal disturbances in extreme ultraviolet (EUV), soft X-ray (SXR), and other wavebands during the solar flare and coronal mass ejection (CME) eruptive events have been observed and simulated extensively during past decades (Liu and Ofman, 2014; Warmuth, 2015)
The electric current distribution on a plane y 0 shows that several structures appear as a result of the upward rise of the magnetic fluxrope (MFR), including the fast shock (FS), the helical current boundary (HCB) and other features
The HCB results from the interaction between the background magnetic field and the upward eruptive magnetic structure

Summary

INTRODUCTION

Coronal disturbances in extreme ultraviolet (EUV), soft X-ray (SXR), and other wavebands during the solar flare and coronal mass ejection (CME) eruptive events have been observed and simulated extensively during past decades (Liu and Ofman, 2014; Warmuth, 2015). In the numerical simulation of EUV disturbances, some physical processes, such as vortices, slow MHD shock wave (SS), and velocity separatrix (VS), has been noticed and should exist as ubiquitous as the fast MHD wave/shock in realistic observations They have not been confirmed by observational studies. Mei et al (2020b) had performed 3D MHD simulation for EUV disturbance and find that the SS is associated with a VS, which separates plasma moving inward to the center of the eruptive source region and plasma moving after the fast shock (FS) These numerical simulations reflect the existence of a velocity distribution with complex structure in the eruptive source region, which results from the interaction among the CME, the FS and other structures.

SETUP OF SIMULATION

NUMERICAL RESULTS

CONCLUSION

DATA AVAILABILITY STATEMENT