Interaction of coronal mass ejections and the solar wind

Abstract

Aims. Our goal is to thoroughly analyse the dynamics of single and multiple solar eruptions, as well as a stealth ejecta. The data were obtained through self-consistent numerical simulations performed in a previous study. We also assess the effect of a different background solar wind on the propagation of these ejecta to Earth. Methods. We calculated all the components of the forces contributing to the evolution of the numerically modelled consecutive coronal mass ejections (CMEs) obtained with the 2.5D magnetohydrodynamics (MHD) module of the code MPI-AMRVAC. We analysed the thermal and magnetic pressure gradients and the magnetic tension dictating the formation of several flux ropes in different locations in the aftermath of the eruptions. These three components were tracked in the equatorial plane during the propagation of the CMEs to Earth. Their interaction with other CMEs and with the background solar wind was also studied. Results. We explain the formation of the stealth ejecta and the plasma blobs (or plasmoids) occurring in the aftermath of solar eruptions. We also address the faster eruption of a CME in one case with a different background wind, even when the same triggering boundary motions were applied, and attribute this to the slightly different magnetic configuration and the large neighbouring arcade. The thermal pressure gradient revealed a shock in front of these slow eruptions, formed during their propagation to 1 AU. The double-peaked magnetic pressure gradient indicates that the triggering method affects the structure of the CMEs and that a part of the adjacent streamer is ejected along with the CME.

Is There a Dynamic Difference between Stealthy and Standard Coronal Mass Ejections?

“…Understanding the dynamics of CMEs and predicting their speeds and transit times from the Sun to the Earth play significant roles in space weather forecasting (Durand-Manterola et al 2017). Studies in CME dynamics generally focus on forces at work during their propagation from the solar corona into interplanetary space (Byrne et al 2010;Carley et al 2012;Shen et al 2012;Talpeanu et al 2022). In the propagation stage, CMEs are thought to be driven by a mixture of the internal Lorentz force and the aerodynamic drag force due to the interaction with the ambient solar wind (Byrne et al 2010;Carley et al 2012;Sachdeva et al 2017).…”

Deflection of Coronal Mass Ejections in Unipolar Ambient Magnetic Fields

“…The deviation of CMEs from a radial trajectory has been often attributed to their deflection (a change of trajectory) at the typically stronger magnetic fields (and Alfvén velocities) of coronal holes (CHs; e.g., Gopalswamy et al 2009;Panasenco et al 2013). Indeed, CMEs that are launched at high latitudes, close to a polar CH, are often seen to deflect toward the heliospheric current sheet (HCS; e.g., Filippov et al 2001;Kilpua et al 2009), and this also has been found in numerical simulations (e.g., Bemporad et al 2012;Zuccarello et al 2012;Talpeanu et al 2022). The amount of deflection seems to depend on several parameters, such as the CH area (width) and the CME speed (e.g., Xie et al 2009;Mohamed et al 2012;Wang et al 2020Wang et al , 2022, and such dependencies have recently been studied systematically in a series of numerical simulations (Sahade et al 2020(Sahade et al , 2021.…”