A magnetostatic sunspot model with ?twisted? field

Solar Physics ◽  
1971 ◽  
Vol 16 (2) ◽  
pp. 398-403 ◽  
Author(s):  
Hong Sik Yun
Keyword(s):  
Sunspot Model ◽  
Twisted Field

Axisymmetric magnetoconvection in a twisted field

1993 ◽  
Vol 253 (-1) ◽  
pp. 297 ◽  
Author(s):  
C. A. Jones ◽  
D. J. Galloway
Keyword(s):  
Twisted Field

The influence of the sunspot model on the Li-abundance

Solar Physics ◽  
1971 ◽  
Vol 21 (1) ◽  
pp. 96-100 ◽  
Author(s):  
G. Stellmacher ◽  
E. Wiehr
Keyword(s):  
Sunspot Model

scholarly journals TWISTED FIELD WORKING Fighting for the Relevance of Being Connected

2011 ◽  
Vol 41 (1) ◽  
Author(s):  
Kirsti Mathiesen Hjemdahl Mathiesen Hjemdahl
Keyword(s):  
Twisted Field

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 A topological analysis of the magnetic breakout model for an eruptive solar flare

2005 ◽  
Vol 461 (2059) ◽  
pp. 2099-2120 ◽  
Author(s):  
Rhona Maclean ◽  
Colin Beveridge ◽  
Dana Longcope ◽  
Daniel Brown ◽  
Eric Priest
Keyword(s):  
Solar Flare ◽  
Magnetic Reconnection ◽  
Topological Analysis ◽  
Null Point ◽  
Topological Approach ◽  
Sunspot Model ◽  
New Class ◽  
Linear Force ◽  
Field Lines

The magnetic breakout model gives an elegant explanation for the onset of an eruptive solar flare, involving magnetic reconnection at a coronal null point which leads to the initially enclosed flux ‘breaking out’ to large distances. In this paper we take a topological approach to the study of the conditions required for this breakout phenomenon to occur. The evolution of a simple delta sunspot model, up to the point of breakout, is analysed through several sequences of potential and linear force-free quasi-static equilibria. We show that any new class of field lines, such as those connecting to large distances, must be created through a global topological bifurcation and derive rules to predict the topological reconfiguration due to various types of bifurcation.

scholarly journals Resistive evolution of toroidal field distributions and their relation to magnetic clouds

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
C. B. Smiet ◽  
H. J. de Blank ◽  
T. A. de Jong ◽  
D. N. L. Kok ◽  
D. Bouwmeester
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Magnetic Clouds ◽  
Twisted Field ◽  
Field Lines ◽  
Rotational Transform ◽  
Universal Pattern ◽  
The Magnetic Field

We study the resistive evolution of a localized self-organizing magnetohydrodynamic equilibrium. In this configuration the magnetic forces are balanced by a pressure force caused by a toroidal depression in the pressure. Equilibrium is attained when this low-pressure region prevents further expansion into the higher-pressure external plasma. We find that, for the parameters investigated, the resistive evolution of the structures follows a universal pattern when rescaled to resistive time. The finite resistivity causes both a decrease in the magnetic field strength and a finite slip of the plasma fluid against the static equilibrium. This slip is caused by a Pfirsch–Schlüter-type diffusion, similar to what is seen in tokamak equilibria. The net effect is that the configuration remains in magnetostatic equilibrium whilst it slowly grows in size. The rotational transform of the structure becomes nearly constant throughout the entire structure, and decreases according to a power law. In simulations this equilibrium is observed when highly tangled field lines relax in a high-pressure (relative to the magnetic field strength) environment, a situation that occurs when the twisted field of a coronal loop is ejected into the interplanetary solar wind. In this paper we relate this localized magnetohydrodynamic equilibrium to magnetic clouds in the solar wind.

Unitary polarities in non commutative twisted field planes

2001 ◽  
Vol 70 (1) ◽  
pp. 59-65
Author(s):  
Eliana Francot
Keyword(s):  
Twisted Field

Magnetodynamical acceleration of cosmic jets: sweeping-magnetic-twist mechanism

1986 ◽  
Vol 64 (4) ◽  
pp. 507-513 ◽  
Author(s):  
Yutaka Uchida ◽  
Kazunari Shibata
Keyword(s):  
Large Scale ◽  
Galactic Nuclei ◽  
High Energy ◽  
Point Of View ◽  
Driving Mechanism ◽  
Star Forming ◽  
Star Forming Regions ◽  
Large Scale Magnetic Field ◽  
Twisted Field ◽  
The Galaxy

Characteristic behavior of cosmic jets predicted by a magnetodynamic mechanism proposed by Uchida and Shibata is discussed in terms of recent observational results of bipolar flows from star-forming regions as examples of low-energy cases. The theoretical model considers the twisting-up of part of the large-scale magnetic field with the driving mechanism being the contracting rotation of the accretion disk around the gravitating center. The twisted field screws out the mass from the surface layers of the disk along the large-scale external field, explaining the observed tuning-fork type of distribution of the cold CO bipolar flows, gradual acceleration of the flows from the vicinity of the disk, and the helical velocity field in the outflows, all of which are not easy to explain by previous hypotheses assuming the wind and blast from the central object. Prospects of application of this mechanism to high-energy jets from active galactic nuclei or such peculiar objects in the galaxy like SS433 or Sco X-1 are discussed from the point of view of the similarity inherent in the mechanism.

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