Pseudostreamer influence on flux rope evolution

Abstract

Context.A highly important aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field topology, which determines the trajectory and morphology of the event. Pseudostreamers (PSs) are coronal magnetic structures formed by arcs of twin loops capped by magnetic field lines from coronal holes of the same polarity that meet at a central spine. They contain a single magnetic null point in the spine, just above the closed field lines, which potentially influences the evolution of nearby flux ropes (FRs). Aims. Because of the impact of magnetic FR eruptions on space weather, we aim to improve current understanding on the deflection of CMEs. To understand the net effect of the PS on FR eruptions is first necessary to study diverse and isolated FR-PS scenarios, which are not influenced by other magnetic structures. Methods. We performed numerical simulations in which a FR structure is in the vicinity of a PS magnetic configuration. The combined magnetic field of the PS and the FR results in the formation of two magnetic null points. We evolve this scenario by numerically solving the magnetohydrodynamic equations in 2.5D. The simulations consider a fully ionised compressible ideal plasma in the presence of a gravitational field and a stratified atmosphere. Results. We find that the dynamic behaviour of the FR can be categorised into three different classes based on the FR trajectories and whether it is eruptive or confined. Our analysis indicates that the magnetic null points are decisive in the direction and intensity of the FR deflection and their hierarchy depends on the topological arrangement of the scenario. Moreover, the PS lobe acts as a magnetic cage enclosing the FR. We report that the total unsigned magnetic flux of the cage is a key parameter defining whether the FR is ejected or not.

Understanding the Deflection of the “Cartwheel CME”: Data Analysis and Modeling

“…Our thorough reconstruction of the initial rising phase and magnetic field allows the identification of a pseudostreamer (PS2) null point located between the initial position of the MFR and the CH. Considering the action of null points in trajectory (e.g., Panasenco et al 2013;Wang et al 2020;Sahade et al 2021Sahade et al , 2022, we presume that this null point was responsible for attracting the MFR toward the CH, which then stopped the MFR deviation and guided it parallel to its magnetic field lines. Then, the peculiar behavior of the 2008 April 9 CME can be explained not only by assuming an asymmetric magnetic reconnection (Capannolo et al 2017), but as a response to the interaction with the magnetic environment near the source region.…”

“…It is generally accepted that neighboring magnetic structures, such as coronal holes (CHs; e.g., Cremades et al 2006;Gopalswamy et al 2009;Sahade et al 2020Sahade et al , 2021 and active regions (ARs; e.g., Kay et al 2015;Möstl et al 2015;Wang et al 2015), can deflect MFRs in longitude and latitude against their position. On the other hand, heliospheric current sheets (e.g., Liewer et al 2015;Wang et al 2020), helmet streamers (e.g., Zuccarello et al 2012;Yang et al 2018), and pseudostreamers (PSs; e.g., Cécere et al 2020;Wang et al 2020;Karna et al 2021;Sahade et al 2022) attract MFRs toward their low magnetic field regions. These responses can be quantified, in strength and direction, by the local and global gradients of the magnetic pressure (Gui et al 2011;Panasenco et al 2013;Liewer et al 2015;Sieyra et al 2020).…”

Understanding the deflection of the `Cartwheel CME': data analysis and modeling

“…Our thorough reconstruction of the initial rising phase and magnetic field allows the identification of a pseudostreamer null point located between the initial position of the MFR and the CH. Considering the action of null points in trajectory (e.g., Panasenco et al 2013;Wang et al 2020;Sahade et al 2021Sahade et al , 2022, we presume that this null point is responsible for attracting the MFR toward the CH, which then stops the MFR deviation and guides it parallel to its magnetic field lines. Then, the peculiar behavior of the 2008-04-09 CME can be explained not only by assuming an asymmetric magnetic reconnection (Capannolo et al 2017), but as a response to the interaction with the magnetic environment near the source region.…”

“…It is generally accepted that neighboring magnetic structures, such as coronal holes (CHs -e.g., Cremades et al 2006;Gopalswamy et al 2009;Sahade et al 2020Sahade et al , 2021 and active regions (ARs -e.g., Kay et al 2015;Möstl et al 2015;Wang et al 2015), can deflect MFRs in longitude and latitude against their position. On the other hand, heliospheric current sheets (e.g., Liewer et al 2015;Wang et al 2020), helmet-streamers (e.g., Zuccarello et al 2012;Yang et al 2018), and pseudostreamers (PSs -e.g., Cécere et al 2020;Wang et al 2020;Karna et al 2021;Sahade et al 2022) attract MFRs toward their low magnetic field regions. This responses can be quantified, in strength and direction, by the local and global gradients of the magnetic pressure (Gui et al 2011;Panasenco et al 2013;Liewer et al 2015;Sieyra et al 2020).…”

Impact of the Solar Activity on the Propagation of ICMEs: Simulations of Hydro, Magnetic and Median ICMEs at the Minimum and Maximum of Activity

“…We can wonder how realistic it is to have a CME injected right in the middle of the current sheet at 0.1 au. Although CMEs have very little chance of being generated at the equator because they may face magnetic trapping (Sahade et al 2022), they can be channeled toward the current sheet if they form close to the border of a streamer or pseudo-streamer (Zuccarello et al 2012). Also, this effect is dominant at the minimum of activity thanks to the dipolar structure of the solar magnetic field, which justifies even more this result for the minimum case (Lavraud & Rouillard 2014).…”