A class of force-free magnetic fields for modeling pre-flare coronal magnetic configurations

Chou, Yu-Chen; Low, B. C.

doi:10.1007/bf00712506

Cited by 8 publications

(10 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is slightly misleading, as a significant fraction of the area that is poorly reproduced contains weak field, so the field lines with no more than a 10% error comprise 32% of the flux (74% in the sphere). Further, from the point of view of reconnection, the FLD shows that the interesting topology is fairly well reproduced, at the expense of Chou & Low (1994) solution (red lines) and for a linear force-free extrapolation of the field ( green lines). Gray scale shows the normal component of the field, with the neutral line in yellow.…”

Section: Case 1: An X-type Separatormentioning

confidence: 94%

“…One part of the QSL corresponds to the surface of the current-loaded sphere; it partitions the volume into field lines along which no current flows and twisted field lines along which a current does flow. The nature of the solution is such that the current is finite throughout the volume, but the current density becomes infinite as the surface of the sphere is approached from the inside (Chou & Low 1994). It is the discontinuous change to zero current density outside the sphere that causes the large displacement gradients across the surface.…”

Section: Case 1: An X-type Separatormentioning

confidence: 98%

“…Specifically, in the notation of Chou & Low (1994), we take ¼ 5:4, r 0 ¼ 1:3L/3, and a ¼ L/2, which is essentially the solution shown in their Figure 7c. The solution is azimuthally symmetric, with the axis of symmetry lying below the boundary for the extrapolations.…”

Section: Case 1: An X-type Separatormentioning

confidence: 99%

“…For our first case, we take the final step in a sequence of nonlinear force-free equilibria described by Chou & Low (1994). Specifically, in the notation of Chou & Low (1994), we take ¼ 5:4, r 0 ¼ 1:3L/3, and a ¼ L/2, which is essentially the solution shown in their Figure 7c.…”

Section: Case 1: An X-type Separatormentioning

confidence: 99%

See 3 more Smart Citations

Quantifying the Performance of Force‐free Extrapolation Methods Using Known Solutions

Barnes

Leka

Wheatland

2006

ApJ

View full text Add to dashboard Cite

We outline a method for quantifying the performance of extrapolation methods for magnetic fields. We extrapolate the field for two model cases, using a linear force-free approach and a nonlinear approach. Each case contains a different topological feature of the field that may be of interest in solar energetic events. We are able to determine quantitatively whether either method is capable of reproducing the topology of the field. In one of our examples, a subjective evaluation of the performance of the extrapolation suggests that it has performed quite well, while our quantitative score shows that this is not the case, indicating the importance of being able to quantify the performance. Our method may be useful in determining which extrapolation techniques are best able to reproduce a force-free field and which topological features can be recovered.

show abstract

Section: Case 1: An X-type Separatormentioning

confidence: 94%

Section: Case 1: An X-type Separatormentioning

confidence: 98%

Section: Case 1: An X-type Separatormentioning

confidence: 99%

Section: Case 1: An X-type Separatormentioning

confidence: 99%

See 2 more Smart Citations

Quantifying the Performance of Force‐free Extrapolation Methods Using Known Solutions

Barnes

Leka

Wheatland

2006

ApJ

View full text Add to dashboard Cite

show abstract

“…photospheric observations, using the SNM as well as another analytic model field configuration (Chou and Low, 1994) as proxy photospheric fields. The presence, location, size and shape of separatrix surfaces and layers as well as X -type separators were considered in determining whether extrapolations, both linear and nonlinear forcefree, did a good job of reproducing the model field.…”

Section: Barnes Et Al (2005b) Considered the Technique Of Extrapolatmentioning

confidence: 99%

Emergence of Twisted Magnetic Flux into the Corona

Gibson¹,

Fan²,

Leka³

2005

View full text Add to dashboard Cite

Public reportingburden for this collection of information is estimated to average 1 hour per response, including the time for reviewing inst e data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other a this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0 1 4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing My valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

show abstract

Solar activity and the corona

1996

Self Cite

View full text Add to dashboard Cite

This review puts together what we have learned about coronal structures and phenomenology to synthesize a physical picture of the corona as a voluminous, thermally and electrically highly-conducting atmosphere responding dynamically to the injection of magnetic flux from below. The synthesis describes complementary roles played by the magnetic heating of the corona, the different types of flares, and the coronal mass ejections as physical processes by which magnetic flux and helicity make their way from below the photosphere into the corona, and, ultimately, into interplanetary space. In these processes, a physically meaningful interplay among dissipative magnetohydrodynamic turbulence, ideal ordered flows, and magnetic helicity determines how and when the rich variety of relatively long-lived coronal structures, spawned by the emerged magnetic flux, will evolve quasi-steadily or erupt with the impressive energies characteristic of flares and coronal mass ejections. Central to this picture is the suggestion, based on recent theoretical and observational works, that the the emerged flux may take the form of a twisted flux rope residing principally in the corona. Such a flux rope is identified with the low-density cavity at the base of a coronal helmet, often but not always encasing a quiescent prominence. The flux rope may either be bodily transported into the corona from below the photosphere, or reform out of a state of flaring turbulence under some suitable constraint of magnetic-helicity conservation. The appeal of this synthesis is its physical simplicity and the manner it relates a large set of diverse phenomena into a self-consistent whole. The implications of this view point are discussed.The topics covered are: the large-scale corona; helmet streamers; quiescent prominences; coronal mass ejections; flares and heating; magnetic reconnection and magnetic helicity; and, the hydromagnetics of magnetic flux emergence.

show abstract

A class of force-free magnetic fields for modeling pre-flare coronal magnetic configurations

Cited by 8 publications

References 33 publications

Quantifying the Performance of Force‐free Extrapolation Methods Using Known Solutions

Quantifying the Performance of Force‐free Extrapolation Methods Using Known Solutions

Emergence of Twisted Magnetic Flux into the Corona

Solar activity and the corona

Contact Info

Product

Resources

About