scholarly journals Magnetic field topology from non-force free extrapolation and magnetohydrodynamic simulation of its eventual dynamics

2018 ◽  
Vol 13 (S340) ◽  
pp. 183-184
Author(s):  
Sushree S. Nayak ◽  
R. Bhattacharyya ◽  
A. Prasad ◽  
Q. Hu
Keyword(s):  
Magnetic Field ◽  
Lorentz Force ◽  
Free Field ◽  
Magnetic Field Topology ◽  
Mhd Simulations ◽  
Extrapolation Scheme ◽  
Magnetohydrodynamic Simulation ◽  
Force Free Field ◽  
Contemporary Standard

AbstractMagnetic reconnections (MRs) for various magnetic field line (MFL) topologies are believed to be the initiators of solar eruptive events like flares and coronal mass ejections (CMEs). Consequently, important is a thorough understanding and quantification of the MFL topology and their evolution which leads to MRs. Contemporary standard is to extrapolate the coronal MFLs using equilibrium models where the Lorentz force on the coronal plasma is zero everywhere. In tandem, a non-force-free-field (NFFF) extrapolation scheme has evolved and allows for a Lorentz force which is non-zero only at the photosphere but asymptotically vanishes with height. The paper reports magnetohydrodynamic (MHD)- simulations initiated by NFFF extrapolation of the coronal MFLs for a flare producing active region NOAA 11158. Interestingly, quasi-separatrix layers (QSLs) which facilitate MRs are detected in the extrapolated MFLs and, here the paper makes an attempt to asses the role of QSLs in the flare onsets.

scholarly journals Study of magnetic field topology of active region 12192 using an extrapolated non-force-free magnetic field

2018 ◽  
Vol 13 (S340) ◽  
pp. 81-82
Author(s):  
A. Prasad ◽  
R. Bhattacharyya ◽  
Q. Hu ◽  
S. S. Nayak ◽  
Sanjay Kumar
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Free Field ◽  
Coronal Magnetic Field ◽  
Solar Photosphere ◽  
Magnetic Field Topology ◽  
Cycle 24 ◽  
Magnetic Null ◽  
The Magnetic Field ◽  
Force Free Field

AbstractThe solar active region (AR) 12192 was one of the most flare productive region of solar cycle 24, which produced many X-class flares; the most energetic being an X3.1 flare on October 24, 2014 at 21:10 UT. Customarily, such events are believed to be triggered by magnetic reconnection in coronal magnetic fields. Here we use the vector magnetograms from solar photosphere, obtained from Heliospheric Magnetic Imager (HMI) to investigate the magnetic field topology prior to the X3.1 event, and ascertain the conditions that might have caused the flare. To infer the coronal magnetic field, a novel non-force-free field (NFFF) extrapolation technique of the photospheric field is used, which suitably mimics the Lorentz forces present in the photospheric plasma. We also highlight the presence of magnetic null points and quasi-separatrix layers (QSLs) in the magnetic field topology, which are preferred sites for magnetic reconnections and discuss the probable reconnection scenarios.

scholarly journals The role of non-axisymmetry of magnetic flux rope in constraining solar eruptions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ze Zhong ◽  
Yang Guo ◽  
M. D. Ding
Keyword(s):  
Magnetic Field ◽  
Lorentz Force ◽  
Flux Rope ◽  
Radial Magnetic Field ◽  
Magnetic Flux Rope ◽  
Background Magnetic Field ◽  
Solar Eruptions ◽  
Magnetohydrodynamic Simulation ◽  
Mass Ejection

AbstractWhether a solar eruption is successful or failed depends on the competition between different components of the Lorentz force exerting on the flux rope that drives the eruption. The present models only consider the strapping force generated by the background magnetic field perpendicular to the flux rope and the tension force generated by the field along the flux rope. Using the observed magnetic field on the photosphere as a time-matching bottom boundary, we perform a data-driven magnetohydrodynamic simulation for the 30 January 2015 confined eruption and successfully reproduce the observed solar flare without a coronal mass ejection. Here we show a Lorentz force component, resulting from the radial magnetic field or the non-axisymmetry of the flux rope, which can essentially constrain the eruption. Our finding contributes to the solar eruption model and presents the necessity of considering the topological structure of a flux rope when studying its eruption behaviour.

scholarly journals Numerical simulations of the CME on 2010 April 8

2012 ◽  
Vol 8 (S294) ◽  
pp. 575-576
Author(s):  
Yingna Su ◽  
Bernhard Kliem ◽  
Adriaan van Ballegooijen ◽  
Edward Deluca
Keyword(s):  
Magnetic Field ◽  
Stable Equilibrium ◽  
Free Field ◽  
Flux Rope ◽  
Stable Model ◽  
Mhd Simulations ◽  
Insertion Method ◽  
Ideal Mhd ◽  
Nonlinear Force ◽  
Force Free Field

AbstractWe present 3D zero-beta ideal MHD simulations of the solar flare/CME event that occurred in Active Region 11060 on 2010 April 8. The initial magnetic configurations of the two simulations are stable nonlinear force-free field and unstable magnetic field models constructed by Su et al. (2011) using the flux rope insertion method. The MHD simulations confirm that the stable model relaxes to a stable equilibrium, while the unstable model erupts as a CME. Comparisons between observations and MHD simulations of the CME are also presented.

scholarly journals Nonlinear force-free modeling of magnetic fields in flare-productive active regions

2015 ◽  
Vol 11 (S320) ◽  
pp. 167-174
Author(s):  
M. S. Wheatland ◽  
S. A. Gilchrist
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Data ◽  
Numerical Solutions ◽  
Free Field ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Nonlinear Force ◽  
The Magnetic Field ◽  
Force Free Field

AbstractWe review nonlinear force-free field (NLFFF) modeling of magnetic fields in active regions. The NLFFF model (in which the electric current density is parallel to the magnetic field) is often adopted to describe the coronal magnetic field, and numerical solutions to the model are constructed based on photospheric vector magnetogram boundary data. Comparative tests of NLFFF codes on sets of boundary data have revealed significant problems, in particular associated with the inconsistency of the model and the data. Nevertheless NLFFF modeling is often applied, in particular to flare-productive active regions. We examine the results, and discuss their reliability.

Studying Magnetic Field Variations Accompanying the 2011 June 7 Eruptive Event, by Using Nonlinear Force-Free Field Modeling

Solar Physics ◽  
2020 ◽  
Vol 295 (4) ◽  
Author(s):  
Y. I. Egorov ◽  
V. G. Fainshtein ◽  
I. I. Myshyakov ◽  
S. A. Anfinogentov ◽  
G. V. Rudenko
Keyword(s):  
Magnetic Field ◽  
Free Field ◽  
Eruptive Event ◽  
Field Modeling ◽  
Nonlinear Force ◽  
Magnetic Field Variations ◽  
Force Free Field

scholarly journals A Storage Process of the Magnetic Energy in the Space Active Regions and Stellar Atmosphere

1990 ◽  
Vol 140 ◽  
pp. 17-19
Author(s):  
Li Zhongyuan
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Free Field ◽  
Stellar Atmosphere ◽  
Mhd Equations ◽  
Static Force ◽  
Specific Expression ◽  
Image Position ◽  
The Magnetic Field ◽  
Force Free Field

A few authors (Barnes and Sturrock, 1972; Ma, 1977; Svestka, 1977) have calculated the quantitative relationship between the static force-free field connecting the magnetic field and the twisting processes. They pointed out that the potential magnetic field without the current may be twisted into the force-free field with the enhanced current produced by the plasma rotation. Li et al. (1982) and Li and Hu (1984) have stated that the processes should be unsteady, and especially that they should not be static. The magnetic Reynold number is usually much larger than 100 in stellar atmosphere (Li et al., 1982). We adopt the following MHD equations: where the force - free factor α (t, r) depends on both, t and r. According to t h e kinematical momentum conservation, the following constraint is easily obtained: where V = (u, v, w) is the velocity field in the cylindrical coordinates. When studying the evolution of the kinematical force - free field, the in fluence of a reasonable flow on the variations of the magnetic field should be taken into account. After some reasonable simplification we deduce the specific expression of the variation law of the toroidal magnetic energy where J1 is the Bessel function of the first order. In the active region, magnetic energy including the term of a twisted effect f(t) is larger than that of the static force - free field.

scholarly journals Solar Flares and Related Coronal Magnetic Field Structures in NOAA 8100

2001 ◽  
Vol 203 ◽  
pp. 341-343
Author(s):  
Y. Yan
Keyword(s):  
Magnetic Field ◽  
Solar Flares ◽  
Free Field ◽  
Coronal Magnetic Field ◽  
New Technique ◽  
Field Reconstruction ◽  
Flare Process ◽  
A New Technique ◽  
Force Free Field

In this paper we describe the available methods for the non-constant-α force-free field reconstruction and study the associations between reconstructed 3-d coronal fields by a new technique and the 2B/X2 flare process from observations in AR 8100 on 4 November 1997.

scholarly journals Hinode magnetic-field observations of solar flares for exploring the energy storage and trigger mechanisms

2015 ◽  
Vol 11 (S320) ◽  
pp. 175-178
Author(s):  
Toshifumi Shimizu ◽  
Satoshi Inoue ◽  
Yusuke Kawabata
Keyword(s):  
Magnetic Field ◽  
Free Field ◽  
Coronal Magnetic Field ◽  
Field Configuration ◽  
Optical Telescope ◽  
Magnetic Field Data ◽  
Trigger Mechanisms ◽  
The Magnetic Field ◽  
Force Free Field ◽  
Chromospheric Flare

AbstractThe spectro-polarimeter in the Hinode Solar Optical Telescope (SOT) is one of the powerful instruments for the most accurate measurements of vector magnetic fields on the solar surface. The magnetic field configuration and possible candidates for flare trigger are briefly discussed with some SOT observations of solar flare events, which include X5.4/X1.3 flares on 7 March 2012, X1.2 flare on 7 January 2014 and two M-class flares on 2 February 2014. Especially, using an unique set of the Hinode and SDO data for the X5.4/X1.3 flares on 7 March 2012, we briefly reviewed remarkable properties observed in the spatial distribution of the photospheric magnetic flux, chromospheric flare ribbons, and the 3D coronal magnetic field structure inferred by non-linear force-free field modeling with the Hinode photospheric magnetic field data.

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