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— Distribution of the magnetic energy density at the heights of 1.06 (upper panel) and 1.16 R ⊙ (lower panel) based on the NLFFF reconstruction. The black cross shows the projected location of the CME source region. The colored crosses (P1-P5) show the projections of the footpoints of the magnetic field lines traced from the reconstructed CME mass centers.
Source publication
We study the role of the coronal magnetic field configuration of an active
region in determining the propagation direction of a coronal mass ejection
(CME). The CME occurred in the active region 11944 (S09W01) near the disk
center on 2014 January 7 and was associated with an X1.2 flare. A new CME
reconstruction procedure based on a polarimetric tec...
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Citations
... A number of studies have shown that the deflection may be caused by the strong magnetic fields in the active region (e.g., Sterling et al. 2011;Gopalswamy et al. 2014;Kay et al. 2015;Möstl et al. 2015;Wang et al. 2015). By analyzing the near-Sun deflection of a CME in connection to the magnetic field configuration in the source active region (AR), Wang et al. (2015) note that the CME was directed away from the AR within 2.5 R e . ...
... A number of studies have shown that the deflection may be caused by the strong magnetic fields in the active region (e.g., Sterling et al. 2011;Gopalswamy et al. 2014;Kay et al. 2015;Möstl et al. 2015;Wang et al. 2015). By analyzing the near-Sun deflection of a CME in connection to the magnetic field configuration in the source active region (AR), Wang et al. (2015) note that the CME was directed away from the AR within 2.5 R e . The work of Gopalswamy et al. (2014) and Möstl et al. (2015) on the CME from 2014 January 7 demonstrated that an observed sizable deflection (of about 37°) with respect to the source region was caused by nearby active region rather than CHs. ...
During their propagation, coronal mass ejections (CMEs) and prominences sometimes display a nonradial motion. During the years after the solar minimum, the CME central position angle tended to be offset closer to the equator compared to that of the associated prominence eruptions (PE). No such effect was observed during solar maximum. The purpose of this paper is to investigate the latitudinal offsets of CMEs with respect to their source regions. We study 256 events from SC 24 and SC 25, listed in the Coordinate Data Analysis Workshop Data Center. We analyzed the CMES radial offset from the associated PEs by comparing their latitudes in the plane of the sky. This work is an extension of the previous work by Gopalswamy et al., but with an independent data set. We have confirmed the systematic equatorward offset of CME from the solar source region for the rising phase of Solar Cycle 25. Our analysis of the relation between CME linear speed and PE-CME latitudinal offset indicated that the velocities of the deflected CMEs are mainly in the range of 200 and 800 km s ⁻¹ . In this study, we compared the nonradial offsets for the rising and decay phases of SC 24 and our analysis has shown that during the decay phase more events deflected toward the pole can be observed. The observed variation is attributed to the presence of a substantial number of low-latitude coronal holes during the decay phase and to the influence from nearby active regions.
... 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. ...
... Nonradial CME trajectories have been also attributed to the presence of asymmetric magnetic fields in the CME source region, which lead to an immediate "channeling" or "asymmetric expansion" of the erupting flux (e.g., Liewer et al. 2015;Wang et al. 2015;Sahade et al. 2022). Indeed, a preeruptive magnetic flux rope (MFR) that is embedded in an asymmetric field adopts a tilted configuration (see, e.g., Figure 4(c) in Titov et al. 2014). ...
The trajectories of coronal mass ejections (CMEs) are often seen to deviate substantially from a purely radial propagation direction. Such deviations occur predominantly in the corona and have been attributed to “channeling” or deflection of the eruptive flux by asymmetric ambient magnetic fields. Here, we investigate an additional mechanism that does not require any asymmetry of the preeruptive ambient field. Using magnetohydrodynamic numerical simulations, we show that the trajectories of CMEs through the solar corona can significantly deviate from the radial direction when propagation takes place in a unipolar radial field. We demonstrate that the deviation is most prominent below ∼15 R ⊙ and can be attributed to an “effective I × B force” that arises from the intrusion of a magnetic flux rope with a net axial electric current into a unipolar background field. These results are important for predictions of CME trajectories in the context of space-weather forecasts, as well as for reaching a deeper understanding of the fundamental physics underlying CME interactions with the ambient fields in the extended solar corona.
... Several factors can deflect an eruption from its radial course (MacQueen et al. 1986;Cremades & Bothmer 2004;Gui et al. 2011;Kay et al. 2015;Sieyra et al. 2020). 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. ...
We study the low corona evolution of the “Cartwheel” coronal mass ejection (CME; 2008 April 9) by reconstructing its three-dimensional path and modeling it with magnetohydrodynamic simulations. This event exhibited a double deflection that has been reported and analyzed in previous works but whose underlying cause remained unclear. The Cartwheel CME traveled toward a coronal hole (CH) and against the magnetic gradients. Using a high-cadence, full-trajectory reconstruction, we accurately determine the location of the magnetic flux rope (MFR) and, consequently, the magnetic environment in which it is immersed. We find a pseudostreamer (PS) structure whose null point may be responsible for the complex evolution of the MFR at the initial phase. From the preeruptive magnetic field reconstruction, we estimate the dynamic forces acting on the MFR and provide a new physical insight into the motion exhibited by the 2008 April 9 event. By setting up a similar magnetic configuration in a 2.5D numerical simulation we are able to reproduce the observed behavior, confirming the importance of the PS null point. We find that the magnetic forces directed toward the null point cause the first deflection, directing the MFR toward the CH. Later, the magnetic pressure gradient of the CH produces the reversal motion of the MFR.
... Several factors can deflect an eruption from its radial course (MacQueen et al. 1986;Cremades & Bothmer 2004;Gui et al. 2011;Kay et al. 2015;Sieyra et al. 2020). 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. ...
We study the low corona evolution of the `Cartwheel' coronal mass ejection (CME; 2008-04-09) by reconstructing its 3D path and modeling it with magneto-hydrodynamic simulations. This event exhibits a double-deflection that has been reported and analyzed in previous works but whose underlying cause remained unclear. The `Cartwheel CME' travels toward a coronal hole (CH) and against the magnetic gradients. Using a high-cadence, full trajectory reconstruction, we accurately determine the location of the magnetic flux rope (MFR) and, consequently, the magnetic environment in which it is immersed. We find a pseudostreamer (PS) structure whose null point may be responsible for the complex evolution of the MFR at the initial phase. From the pre-eruptive magnetic field reconstruction, we estimate the dynamic forces acting on the MFR and provide a new physical insight on the motion exhibited by the 2008-04-09 event. By setting up a similar magnetic configuration in a 2.5D numerical simulation we are able to reproduce the observed behavior, confirming the importance of the PS null point. We find that the magnetic forces directed toward the null point cause the first deflection, directing the MFR towards the CH. Later, the magnetic pressure gradient of the CH produces the reversal motion of the MFR.
... It is widely known that the magnetic structures in the vicinity of FRs are capable of deflecting them both in latitude and longitude. While coronal holes (e.g., Cremades et al. 2006;Gopalswamy et al. 2009;Sahade et al. 2020Sahade et al. , 2021 and active regions (e.g., Kay et al. 2015;Möstl et al. 2015;Wang et al. 2015) deflect FRs against their location, 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., Bi et al. 2013;Wang 2015;Cécere et al. 2020;Wang et al. 2020) attract FRs to their low magnetic energy regions. Combined effects of the several structures at different heights can be seen in, for example, Sieyra et al. (2020). ...
... All the final paths are opposite to the location of the coronal hole by the "channelling" of the magnetic field lines, i.e., the FR is guided to follow the least resistance path. Möstl et al. (2015) and Wang et al. (2015) studied an event on 2014 January 7 whose deflection seems to be caused by the magnetic pressure gradient from a nearby active region and whose final path is also channelled by the configuration of the magnetic field lines to the least resistance direction. Shen et al. (2011) concluded that the trajectory in the early stages is influenced by the background magnetic energy gradients, inducing the CME to propagate towards the region with the lowest magnetic energy density. ...
A critical aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field, which determines the trajectory and morphology of the eruptive 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, potentially influencing the evolution of nearby flux ropes (FRs). 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. 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. 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.
... We note that the first short lived and compact brightenings (flare precursors) appeared at the site of eruption about 20 minutes prior to the flare onset indicating on possible pre-flare activity at this location. This event was at the focus of two case (Wang et al. 2015;Zheng et al. 2016) and several statistical (Falconer et al. 2016;Toriumi et al. 2017b;Toriumi & Takasao 2017;Lu et al. 2019;Duan et al. 2019bDuan et al. , 2021 studies. The flare erupted at the outskirt of the AR, south-west of the leading sunspot and away from the major PIL. ...
... Thus the double arc instability (Ishiguro & Kusano 2017), being independent of the decay index may realize conditions for tether-cutting reconnection as an onset mechanism of solar eruptions. Wang et al. (2015) analyzed the same AR as that studied here and argued that open field structures detected in their extrapolations could be a guide for the eruption fields (see also Möstl et al. 2015). Our extrapolations did not include open field lines at the site of the eruption, however, we note that Fleishman et al. (2019) concluded that the NLFFF extrapolation routine tends to produce a more "closed" magnetic field configuration as compared to the test data. ...
... We therefore speculate that the ejecta was non-radially escaping from underneath the extended sunspot fields, along a channel with a low decay index. Although details of our and Wang et al. (2015) extrapolations may differ, they both agree on the non-radial propagation of the ejecta and strong influence of the sunspot fields. We thus further confirm the important role that the large scale magnetic environment play in the low corona in defining the direction of a magnetic eruption. ...
Using multi-wavelength observations, we analysed magnetic field variations associated with a gradual X1.2 flare that erupted on January 7, 2014 in active region (AR) NOAA 11944 located near the disk center. A fast coronal mass ejection (CME) was observed following the flare, which was noticeably deflected in the southwest direction. A chromospheric filament was observed at the eruption site prior to and after the flare. We used SDO/HMI data to perform non-linear force-free field (NLFFF) extrapolation of coronal magnetic fields above the AR and to study the evolution of AR magnetic fields prior to the eruption. The extrapolated (model) data allowed us to detect signatures of several magnetic flux ropes (MFRs) present at the eruption site several hours before the event. The eruption site was located under slanted sunspot fields with a varying decay index of 1.0-1.5. That might have caused the erupting fields to slide along this slanted magnetic boundary rather than vertically erupt, thus explaining the slow rise of the flare as well as the observed direction of the resulting CME. We employed sign-singularity tools to quantify the evolutionary changes in the model twist and observed current helicity data, and found rapid and coordinated variations of current systems in both data sets prior to the event as well as their rapid exhaustion after the event onset.
... Many solar researchers have pointed out the importance of highly sheared PILs (e.g., Hagyard et al. 1984;Tanaka 1991;Zirin & Wang 1993;Falconer et al. 2002;Schrijver 2007). The formation process of the δ-spots and temporal evolution of the ARs associated with the δ-spots are reviewed by Wang et al. (2015). Toriumi & Takasao (2017) numerically carried flux emergence simulations to clarify the formation of δ-spots with sheared PILs in the surface layer. ...
The properties of the sheared/guide field magnetic reconnection (MRX) are investigated with two-dimensional MHD simulation. We simulate the spontaneous evolution from the isothermal current sheet (CS) equilibrium in which distribution of the thermodynamical quantities is symmetric about the CS. The magnetic shear is characterized by two parameters: the shear parameter and the asymmetry parameter. The asymmetry of the Alfvén speed ( V A0x ) perpendicular to the X-line along the CS is essential. We focus on the asymptotic self-similarly expanding phase of the evolution. This research is unique for the discussion based on the consistency across the entire MRX system, although the sheared MRX has been studied since the early 1980s. In addition to reconfirmation of the previously reported properties of the sheared MRX, the following new properties are found. (1) The reconnection jet changes to the “core–envelope structure” (a high-density core with a low-density envelope) for the sheared symmetric V A0x case but the “two-layered structure” (the high-speed, low-density layer and the medium-speed, high-density layer) for the asymmetric V A0x case. (2) The parameter dependence of the reconnection rate is clarified. The MRX is fastest for the symmetric case and slows as the asymmetry increases for any fixed shear angle. For the symmetric case, the reconnection rate has a monotonically decreasing dependence on the shear angle. (3) In the asymmetric case, the plasmas from both sides of the CS coexist on the same magnetic field lines in the larger V A0x side plasmoid. This characteristic structure suggests an efficient plasma mixing when the plasmoid breaks.
... This is because the extrapolation quality of the NLFFF model decreases near the side boundaries(e.g., see Duan et al. 2018), while the potential field model is found to be more reasonable if one focuses on the large-scale magnetic topology. As can be seen in Figure 10, with the multiple polarity distribution, the MFR overlying the magnetic field has a null-point-like magnetic topology, which is also found by Wang et al. (2015). The thick lines colored in purple show the flux immediately above the fan surface of the null-like topology, and the thin green lines are the closed flux immediately below the fan surface, which is a 3D magnetic topology interface. ...
... The subsequent evolution is characterized by a decrease of the twisted magnetic flux, which might be caused by a major eruption with an X-class flare that occurred on 2014 January 7. Although it has been conjectured that it is the large inter-AR MFR that triggers the eruption(e.g., Wang et al. 2015;Jiang et al. 2019), we did not find concrete evidence supporting this. On the one hand, the AIA observations show no significant ejections of the MFR-related filament during the flare; on the other hand, our reconstructed field shows the sigmoidal MFR still exists for hours after the flare and only disappears near the end of January 8, thus it is likely that the decay of the MFR is a result of the eruption, which strongly disturbs the MFR's background field. ...
Magnetic flux rope (MFR) has been recognized as the key magnetic configuration of solar eruptions. While pre-eruption MFRs within the core of solar active regions (ARs) have been widely studied, those existing between two ARs, i.e., the intermediate ones in weak-field regions, were rarely studied. There are also major eruptions that occurred in such intermediate regions and study of the MFR there will help us understand the physics mechanism underlying the eruptions. Here, with a nonlinear force-free field reconstruction of solar coronal magnetic fields, we tracked the five-day evolution covering the full life of a large-scale inter-AR MFR forming between ARs NOAA 11943 and 11944, which is closely cospatial with a long sigmoidal filament channel and an eruptive X1.2 flare occurring on 2014 January 7. Through topological analysis of the reconstructed 3D magnetic field, it is found that the MFR begins to form early on 2014 January 6; then with its magnetic twist degree continuously increasing for over 30 hr, it becomes highly twisted with field lines winding numbers approaching six turns, which might be the highest twisting degree in extrapolated MFRs that have been reported in the literature. The formation and strength of the MFR are attributed to a continuous sunspot rotation of AR 11944 and flux cancellation between the two ARs. The MFR and its associated filaments exhibit no significant change across the flare time, indicating it is not responsible for the flare eruption. After the flare, the MFR slowly disappears, possibly due to the disturbance by the eruption.
... In addition to these causes, recent studies have demonstrated that CMEs are also deflected by strong magnetic fields from active regions in the locations of the CME source (e.g. Möstl et al., 2015;Wang et al., 2015;Kay, Opher, and Evans, 2015;Kay et al., 2017), with the magnitude of the deflection being inversely related to CME speed and mass. This was previously suggested by Xie et al. (2009) and Kilpua et al. (2009). ...
The analysis of the deflection of coronal mass ejection (CME) events plays an important role in the improvement of the forecasting of their geo-effectiveness. Motivated by the scarcity of comprehensive studies of CME events with a focus on the governing conditions that drive deflections during their early stages, we performed an extensive analysis of 13 CME events that exhibited large deflections during their early development in the low corona. The study was carried out by exploiting solar-corona-imaging observations at different heights and wavelengths from instruments onboard several space- and ground-based solar observatories, namely the Project for Onboard Autonomy 2 (PROBA2), Solar Dynamics Observatory (SDO), Solar TErrestrial RElations Observatory (STEREO), Solar and Heliospheric Observatory (SOHO) spacecraft, and from the National Solar Observatory (NSO). The selected events were observed between October 2010 and September 2011, to take advantage of the location in near quadrature of the STEREO spacecraft and Earth in this time period. In particular, we determined the 3D trajectory of the front envelope of the CMEs and their associated prominences with respect to their solar sources by means of a forward-modeling and tie-pointing tool, respectively. By using a potential-field source-surface model, we estimated the coronal magnetic fields of the ambient medium through which the events propagate to investigate the role of the magnetic-energy distribution in the non-radial propagation of both structures (front envelope and prominence) and in their kinematic properties. The ambient magnetic environment during the eruption and early stages of the events is found to be crucial in determining the trajectory of the CME events, in agreement with previous reports.
... Sometimes CMEs are observed to be deflected during their propagation (i.e., Gopalswamy, Mäkelä, et al., 2009;Gui et al., 2011;Kay et al., 2017;Lugaz et al., 2012;Wang et al., 2011Wang et al., , 2015Yang et al., 2018). For deflection in interplanetary space, it is suggested that interaction between a CME and the large-scale background solar wind plays a role (i.e., Lugaz et al., 2012;Wang et al., 2004). ...
... It should be pointed out that a CME may have an initial non-radial propagation due to the properties of the related source region (i.e., Wang et al., 2015;Zuccarello et al., 2012). Zuccarello et al. (2012) found that the filament-related CME on 21 September 2009 erupted non-radially and then was deflected about 15°toward the HCS in the near corona due to the imbalance in the magnetic pressure and tension forces. ...
... Zuccarello et al. (2012) found that the filament-related CME on 21 September 2009 erupted non-radially and then was deflected about 15°toward the HCS in the near corona due to the imbalance in the magnetic pressure and tension forces. Wang et al. (2015) also found that the flare-related CME on 7 January 2014 changes its propagation direction by around 28°in latitude and 43°in longitude near the Sun attributing this to the "channeling" by the AR CMF rather than to deflection by nearby structures. In addition, besides the CME deflections, the ambient magnetic field configuration can effect the rotation and expansion of CMEs and lead to anisotropic expansion or deformation (i.e., Cremades et al., 2020;Kay et al., 2017;Zuccarello et al., 2012), which should be taken into consider and will be discussed in the future. ...
Solar coronal mass ejections (CMEs) are sometimes deflected during their propagation. This deflection may be the consequence of an interaction between the CME and the ambient coronal field, for example, a coronal hole, or the solar wind. The coronal magnetic field configuration is computed from daily synoptic maps of magnetic field from SOHO/MDI and SDO/HMI using a Potential Field Source Surface model. We analyze 30 halo‐CMEs whose deflection angle exceeds 90° by comparing the ambient magnetic field configuration and the measurement position angles of the CMEs. We find that the deflection of 87% of the CMEs (26 of 30) is consistent with the ambient magnetic field configuration, agreeing with previous studies. Of these 26, 69% are deflected toward the heliospheric current sheet, the boundary between the magnetic field polarities, and 31% toward a pseudo‐streamer, the boundary between same‐polarity magnetic field regions. This implies that the ambient coronal magnetic field configuration plays an important role in the deflection of CMEs and that the current sheet configuration is more important than a pseudo‐streamer. Of the 26 CMEs, the average and standard deviation of the minimum values of the deflection angle in three dimensions relative to an initially radial trajectory are 28° and 14°, respectively.
