Magnetic flux ropes in the solar corona: structure and evolution toward eruption

Li, Rui

doi:10.1088/1674-4527/20/10/165

Cited by 81 publications

(60 citation statements)

References 494 publications

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“…A flare-related eruption of a pre-existing flux rope may appear in different guises (for a review see Liu 2020). It may erupt as a whole, or only partly (for observation-based studies see, e.g., Sun et al 2012;Liu et al 2015, respectively), and even different portions of a flux rope may be ejected during subsequent eruptions (for observation-based studies see, e.g., Cheng et al 2013;Temmer et al 2017).…”

Section: Discussion Of the Results And Our Interpretation Of The Eventmentioning

confidence: 99%

2019 International Women’s Day event

Dumbović

Veronig

Podladchikova

et al. 2021

A&A

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Context. We present a detailed analysis of an eruptive event that occurred on 2019 March 8 in the active region AR 12734, which we refer as the International Women's Day event. The event under study is intriguing based on several aspects: 1) low-coronal eruptive signatures come in "pairs,' namely, there is a double-peaked flare, two coronal dimmings, and two extreme ultraviolet (EUV) waves; 2) although the event is characterized by a complete chain of eruptive signatures, the corresponding coronagraphic signatures are weak; and 3) although the source region of the eruption is located close to the center of the solar disc and the eruption is thus presumably Earth-directed, heliospheric signatures are very weak with very weak Earth impact. Aims. In order to understand the initiation and evolution of this particular event, we performed a comprehensive analysis using a combined observational-modeling approach. Methods. We analyzed a number of multi-spacecraft and multi-instrument (both remote-sensing and in situ) observations, including soft X-ray, EUV, radio and white-light emission, as well as plasma, magnetic field, and particle measurements. We employed 3D nonlinear force-free (NLFF) modeling to investigate the coronal magnetic field configuration in and around the active region, the graduated cylindrical shell (GCS) model to make a 3D reconstruction of the CME geometry, and the 3D magnetohydrodynamical (MHD) numerical model EUropean Heliospheric FORecasting Information Asset (EUHFORIA) to model the background state of the heliosphere. Results. Our results reveal a two-stage C1.3 flare, associated with two EUV waves that occur in close succession and two-stage coronal dimmings that evolve co-temporally with the flare and type II and III radio bursts. Despite its small GOES class, a clear drop in magnetic free energy and helicity is observed during the flare. White light observations do not unambiguously indicate two separate CMEs, but rather a single entity most likely composed of two sheared and twisted structures corresponding to the two eruptions observed in the low corona. The corresponding interplanetary signatures are that of a small flux rope (SFR) with indications of strong interactions with the ambient plasma, which result in a negligible geomagnetic impact. Conclusions. Our results indicate two subsequent eruptions of two systems of sheared and twisted magnetic fields, which already begin to merge in the upper corona and start to evolve further out as a single entity. The large-scale magnetic field significantly influences both the early and the interplanetary evolution of the structure. During the first eruption, the stability of the overlying field was disrupted, enabling the second eruption. We find that during the propagation in the interplanetary space the large-scale magnetic field, that is, the location of heliospheric current sheet (HCS) between the AR and the Earth, is likely to influence propagation, along with the evolution of the erupted structure(s).

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Section: Discussion Of the Results And Our Interpretation Of The Eventmentioning

confidence: 99%

2019 International Women’s Day event

Dumbović

Veronig

Podladchikova

et al. 2021

A&A

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“…The results of our discussions form the core of this manuscript. We do not attempt to provide a comprehensive review of CME initiation and formation processes since there exist several recent excellent reviews on the matter (Chen, 2011;Cheng et al, 2017;Manchester et al, 2017;Green et al, 2018;Archontis and Syntelis, 2019;Georgoulis et al, 2019;Liu, 2020). We focus on three key questions: (1) what constitutes an MFR or SMA?…”

Section: Introductionmentioning

confidence: 99%

Decoding the Pre-Eruptive Magnetic Field Configurations of Coronal Mass Ejections

et al. 2020

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A clear understanding of the nature of the pre-eruptive magnetic field configurations of Coronal Mass Ejections (CMEs) is required for understanding and eventually predicting solar eruptions. Only two, but seemingly disparate, magnetic configurations are considered viable; namely, sheared magnetic arcades (SMA) and magnetic flux ropes (MFR). They can form via three physical mechanisms (flux emergence, flux cancellation, helicity condensation). Whether the CME culprit is an SMA or an MFR, however, has been strongly debated for thirty years. We formed an International Space Science Institute (ISSI) team to address and resolve this issue and report the outcome here. We review the status of the field across modeling and observations, identify the open and closed issues, compile lists of SMA and MFR observables to be tested against observations and outline research activities to close the gaps in our current understanding. We propose that the combination of multi-viewpoint multi-thermal coronal observations and multiheight vector magnetic field measurements is the optimal approach for resolving

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“…Solar eruptions are spectacular manifestation of explosive release of magnetic energy in the Sun's atmosphere, i.e., the solar corona, and therefore, unveiling the relevant magnetic field structures and their evolution holds a central position in the study of solar eruptions. Magnetic flux rope (MFR), a bundle of twisted magnetic field lines winding around a common axis with the same sign, is believed to be a fundamental structure in solar eruptions [1][2][3], especially in those which successfully produce coronal mass ejections (CMEs). By reconstruction of the cross section of ICME (i.e., CMEs that evolves into the inter-planetary space) from the in-situ data obtained by satellites passing through the ICME, it has been well established that typical ICMEs have structure of highly twisted MFR (e.g., [4,5]).…”

Section: Introductionmentioning

confidence: 99%

Formation of Magnetic Flux Rope During Solar Eruption. I. Evolution of Toroidal Flux and Reconnection Flux

et al. 2021

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Magnetic flux ropes (MFRs) constitute the core structure of coronal mass ejections (CMEs), but hot debates remain on whether the MFR forms before or during solar eruptions. Furthermore, how flare reconnection shapes the erupting MFR is still elusive in three dimensions. Here we studied a new MHD simulation of CME initiation by tether-cutting magnetic reconnection in a single magnetic arcade. The simulation follows the whole life, including the birth and subsequent evolution, of an MFR during eruption. In the early phase, the MFR is partially separated from its ambient field by a magnetic quasi-separatrix layer (QSL) that has a double-J shaped footprint on the bottom surface. With the ongoing of the reconnection, the arms of the two J-shaped footprints continually separate from each other, and the hooks of the J shaped footprints expand and eventually become closed almost at the eruption peak time, and thereafter the MFR is fully separated from the un-reconnected field by the QSL. We further studied the evolution of the toroidal flux in the MFR and compared it with that of the reconnected flux. Our simulation reproduced an evolution pattern of increase-to-decrease of the toroidal flux, which is reported recently in observations of variations in flare ribbons and transient coronal dimming. The increase of toroidal flux is owing to the flare reconnection in the early phase that transforms the sheared arcade to twisted field lines, while its decrease is a result of reconnection between field lines in the interior of the MFR in the later phase.

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Magnetic flux ropes in the solar corona: structure and evolution toward eruption

Cited by 81 publications

References 494 publications

2019 International Women’s Day event

2019 International Women’s Day event

Decoding the Pre-Eruptive Magnetic Field Configurations of Coronal Mass Ejections

Formation of Magnetic Flux Rope During Solar Eruption. I. Evolution of Toroidal Flux and Reconnection Flux

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