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

2021 ◽  
Vol 9 ◽  
Author(s):  
Chaowei Jiang ◽  
Jun Chen ◽  
Aiying Duan ◽  
Xinkai Bian ◽  
Xinyi Wang ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Early Phase ◽  
Flux Rope ◽  
Three Dimensions ◽  
Bottom Surface ◽  
Peak Time ◽  
Magnetic Flux Ropes ◽  
Twisted Field ◽  
Solar Eruptions ◽  
Field Lines

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.

scholarly journals Laboratory simulation of solar magnetic flux rope eruptions

2010 ◽  
Vol 6 (S273) ◽  
pp. 483-486
Author(s):  
S. K. P. Tripathi ◽  
W. Gekelman
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Magnetized Plasma ◽  
Three Dimensions ◽  
Laboratory Simulation ◽  
Laboratory Plasma ◽  
Magnetic Flux Ropes ◽  
Solar Prominences ◽  
Plasma Experiment ◽  
Spatio Temporal

AbstractA laboratory plasma experiment has been constructed to simulate the eruption of arched magnetic flux ropes (AMFRs e.g., coronal loops, solar prominences) in an ambient magnetized plasma. The laboratory AMFR is produced using an annular hot LaB6 cathode and an annular anode in a vacuum chamber which has additional electrodes to produce the ambient magnetized plasma. Two laser beams strike movable carbon targets placed behind the annular electrodes to generate controlled plasma flows from the AMFR footpoints that drives the AMFR eruption. The experiment operates with a 0.5 Hz repetition rate and is highly reproducible. Thus, time evolution of the AMFR is recorded in three-dimensions with high spatio-temporal resolutions using movable diagnostic probes. Experimental results demonstrate outward expansion of the AMFR, release of its plasma to the background, and excitation of fast magnetosonic waves during the eruption.

scholarly journals Small-scale Magnetic Flux Ropes and Their Properties Based on In Situ Measurements from the Parker Solar Probe

2022 ◽  
Vol 924 (2) ◽  
pp. 43
Author(s):  
Yu Chen ◽  
Qiang Hu
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Residual Energy ◽  
In Situ Measurements ◽  
Small Scale ◽  
Flux Function ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Field Lines

Abstract We report small-scale magnetic flux ropes via the in situ measurements from the Parker Solar Probe during the first six encounters, and present additional analyses to supplement our prior work in Chen et al. These flux ropes are detected by the Grad–Shafranov-based algorithm, with their durations and scale sizes ranging from 10 s to ≲1 hr and from a few hundred kilometers to 10−3 au, respectively. They include both static structures and those with significant field-aligned plasma flows. Most structures tend to possess large cross helicity, while the residual energy is distributed over wide ranges. We find that these dynamic flux ropes mostly propagate in the antisunward direction relative to the background solar wind, with no preferential signs of magnetic helicity. The magnetic flux function follows a power law and is proportional to scale size. We also present case studies showing reconstructed two-dimensional (2D) configurations, which confirm that both the static and dynamic flux ropes have a common configuration of spiral magnetic field lines (also streamlines). Moreover, the existence of such events hints at interchange reconnection as a possible mechanism for generating flux rope-like structures near the Sun. Lastly, we summarize the major findings, and discuss the possible correlation between these flux rope-like structures and turbulence due to the process of local Alfvénic alignment.

scholarly journals Observations of Magnetic Flux Ropes Opened or Disconnected From the Sun by Magnetic Reconnection in Interplanetary Space

2021 ◽  
Vol 9 ◽  
Author(s):  
Hengqiang Feng ◽  
Yan Zhao ◽  
Jiemin Wang ◽  
Qiang Liu ◽  
Guoqing Zhao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Interplanetary Space ◽  
Closed Field ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Solar Eruptions ◽  
Wind Spacecraft ◽  
Field Lines

During solar eruptions, many closed magnetic flux ropes are ejected into interplanetary space, which contribute to the heliospheric magnetic field and have important space weather effect because of their coherent magnetic field. Therefore, understanding the evolution of these closed flux ropes in the interplanetary space is important. In this paper, we examined all the magnetic and plasma data measured in 1997 by the Wind spacecraft and identified 621 reconnection exhausts. Of the 621 reconnection events, 31 were observed at the boundaries of magnetic flux ropes and were thought to cause the opening or disconnection magnetic field lines of the adjacent ropes. Of the 31 magnetic reconnection events, 29 were interchange reconnections and the closed field lines of these related flux ropes were opened by them. Only 2 of the 31 magnetic reconnection events disconnected the opened field lines of the original flux ropes. These observations indicate that interchange reconnection and disconnection may be two important mechanisms changing the magnetic topology of the magnetic flux ropes during their propagation during the interplanetary space.

scholarly journals Comparison of counterstreaming suprathermal electron signatures of ICMEs with and without magnetic cloud: are all ICMEs flux ropes?

2019 ◽  
Vol 632 ◽  
pp. A129 ◽  
Author(s):  
Jiemin Wang ◽  
Yan Zhao ◽  
Hengqiang Feng ◽  
Qiang Liu ◽  
Zhanjun Tian ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Magnetic Flux ◽  
Flux Rope ◽  
The Sun ◽  
Magnetic Flux Rope ◽  
Suprathermal Electron ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Field Lines ◽  
Disordered Magnetic

Context. Magnetic clouds (MCs), as in large-scale interplanetary magnetic flux ropes, are usually still connected to the Sun at both ends near 1 AU. Many researchers believe that all nonMC interplanetary coronal mass ejections (ICMEs) also have magnetic flux rope structures, which are inconspicuous because the observing spacecraft crosses the flanks of the rope structures. If so, the field lines of nonMC ICMEs should also usually be connected to the Sun at both ends. Aims. We want to know whether or not the field lines of most nonMC ICMEs are still connected to the Sun at both ends. Methods. This study examined the counterstreaming suprathermal electron (CSE) signatures of 272 ICMEs observed by the Advanced Composition Explorer (ACE) spacecraft from 1998 to 2008 and compared the CSE signatures of MCs and nonMC ICMEs. Results. Results show that only 10 of the 101 MC events (9.9% ) and 75 of the 171 nonMC events (43.9%) have no CSEs. Moreover, 21 of the nonMC ICMEs have high CSE percentages (more than 70%) and show relatively stable magnetic field components with slight rotations, which are in line with the expectations that the observing spacecraft passes through the flank of magnetic flux ropes. Therefore, the 21 events may be magnetic flux ropes but the ACE spacecraft passes through their flanks of magnetic flux ropes. Conclusions. Considering that most other nonMC events have disordered magnetic fields, we suggest that some nonMC ICMEs inherently have disordered magnetic fields, and therefore no magnetic flux rope structures.

scholarly journals When do solar erupting hot magnetic flux ropes form?

2020 ◽  
Vol 642 ◽  
pp. A109 ◽  
Author(s):  
A. Nindos ◽  
S. Patsourakos ◽  
A. Vourlidas ◽  
X. Cheng ◽  
J. Zhang
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Flare Activity ◽  
Solar Dynamics Observatory ◽  
Magnetic Flux Ropes ◽  
Morphological Criteria ◽  
Flux Ropes ◽  
Solar Eruptions ◽  
Solar Dynamics ◽  
Mass Ejection

Aims. We investigate the formation times of eruptive magnetic flux ropes relative to the onset of solar eruptions, which is important for constraining models of coronal mass ejection (CME) initiation. Methods. We inspected uninterrupted sequences of 131 Å images that spanned more than eight hours and were obtained by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to identify the formation times of hot flux ropes that erupted in CMEs from locations close to the limb. The appearance of the flux ropes as well as their evolution toward eruptions were determined using morphological criteria. Results. Two-thirds (20/30) of the flux ropes were formed well before the onset of the eruption (from 51 min to more than eight hours), and their formation was associated with the occurrence of a confined flare. We also found four events with preexisting hot flux ropes whose formations occurred a matter of minutes (from three to 39) prior to the eruptions without any association with distinct confined flare activity. Six flux ropes were formed once the eruptions were underway. However, in three of them, prominence material could be seen in 131 Å images, which may indicate the presence of preexisting flux ropes that were not hot. The formation patterns of the last three groups of hot flux ropes did not show significant differences. For the whole population of events, the mean and median values of the time difference between the onset of the eruptive flare and the appearance of the hot flux rope were 151 and 98 min, respectively. Conclusions. Our results provide, on average, indirect support for CME models that involve preexisting flux ropes; on the other hand, for a third of the events, models in which the ejected flux rope is formed during the eruption appear more appropriate.

scholarly journals Small-scale Magnetic Flux Ropes with Field-aligned Flows via the PSP In-situ Observations

2021 ◽  
Author(s):  
Yu Chen ◽  
Qiang Hu ◽  
Lingling Zhao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Rope ◽  
Local Magnetic Field ◽  
Small Scale ◽  
Magnetic Flux Rope ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Field Lines

<p>Magnetic flux rope, formed by the helical magnetic field lines, can sometimes remain its shape while carrying significant plasma flow that is aligned with the local magnetic field. We report the existence of such structures and static flux ropes by applying the Grad-Shafranov-based algorithm to the Parker Solar Probe (PSP) in-situ measurements in the first five encounters. These structures are detected at heliocentric distances, ranging from 0.13 to 0.66 au, in a total of 4-month time period. We find that flux ropes with field-aligned flows have certain properties similar to those of static flux ropes, such as the decaying relations of the magnetic fields within structures with respect to heliocentric distances. Moreover, these events are more likely with magnetic pressure dominating over the thermal pressure and occurring more frequently in the relatively fast-speed solar wind. Taking into account the high Alfvenicity, we also compare these events with switchbacks and present the cross-section maps via the new Grad-Shafranov type reconstruction. Finally, the possible evolution and relaxation of the magnetic flux rope structures are discussed.</p>

scholarly journals Structure and Topology of Magnetic Fields in Solar Prominences

2013 ◽  
Vol 8 (S300) ◽  
pp. 127-134 ◽  
Author(s):  
Adriaan A. van Ballegooijen ◽  
Yingna Su
Keyword(s):  
Magnetic Flux ◽  
Flux Rope ◽  
Time Dependent ◽  
Magnetic Flux Rope ◽  
Magnetic Flux Ropes ◽  
And Topology ◽  
Solar Prominences ◽  
Magnetic Elements ◽  
Dependent Model ◽  
Time Dependent Model

AbstractRecent observations and models of solar prominences are reviewed. The observations suggest that prominences are located in or below magnetic flux ropes that lie horizontally above the PIL. However, the details of the magnetic structure are not yet fully understood. Gravity likely plays an important role in shaping the vertical structures observed in quiescent prominences. Preliminary results from a time-dependent model describing the interaction of a magnetic flux rope with photospheric magnetic elements are presented.

scholarly journals Microwave indicator of potential geoeffectiveness and magnetic flux-rope structure of a solar active region

2021 ◽  
Vol 7 (1) ◽  
pp. 3-12
Author(s):  
Anastasiia Kudriavtseva ◽  
Ivan Myshyakov ◽  
Arkadiy Uralov ◽  
Victor Grechnev
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Neutral Line ◽  
Flux Rope ◽  
Coronal Magnetic Field ◽  
Horizontal Magnetic Field ◽  
Magnetic Flux Rope ◽  
Magnetic Flux Ropes ◽  
Class Flare

We analyze the presence of a microwave neutral-line-associated source (NLS) in a super-active region NOAA 12673, which produced a number of geo-effective events in September 2017. To estimate the NLS position, we use data from the Siberian Radioheliograph in a range 4–8 GHz and from the Nobeyama Radioheliograph at 17 GHz. Calculation of the coronal magnetic field in a non-linear force-free approximation has revealed an extended structure consisting of interconnected magnetic flux ropes, located practically along the entire length of the main polarity separation line of the photospheric magnetic field. NLS is projected into the region of the strongest horizontal magnetic field, where the main energy of this structure is concentrated. During each X-class flare, the active region lost magnetic helicity and became a CME source.

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