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Harvey, K. L.; Jones, H. P.; Schrijver, Carolus J.; Penn, Matthew

doi:10.1023/a:1005237719407

Cited by 67 publications

(61 citation statements)

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“…In both the shape of the dipped field lines is determined by the balance between magnetic and gravitational forces. Many authors have constructed magneto-hydrostatic (MHS) models of prominence threads based on the Kippenhahn-Schlüter model (e.g., Malherbe and Priest, 1983;Heinzel and Anzer, 2001;Heinzel et al, 2005;Low and Petrie, 2005). Another example is the "normal polarity" flux rope model by Low and Zhang (2002).…”

Section: Models Of Prominence Magnetic Structurementioning

confidence: 99%

“…However, this model does not provide a satisfactory explanation of active-region prominences, which are too short to support the thermal non-equilibrium process with typical values of the heating scale, or of the vertical structure and dynamics of hedge-row prominences. Barbs could be consistent with thermal non-equilibrium if they are composed of vertically aligned dips in otherwise horizontal flux tubes (Heinzel and Anzer, 2001), as long as the dips are deep enough to trap the condensed matter: for example, in photospheric "bald patches" near parasitic polarity sites van Ballegooijen, 2004;. This process could occur in any favorable magnetic structure, but thus far has been considered systematically only within the context of the sheared arcade model (section 2.2).…”

Section: Evaporation-condensation Modelsmentioning

confidence: 99%

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Physics of Solar Prominences: II—Magnetic Structure and Dynamics

et al. 2010

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Observations and models of solar prominences are reviewed. We focus on non-eruptive prominences, and describe recent progress in four areas of prominence research: (1) magnetic structure deduced from observations and models, (2) the dynamics of prominence plasmas (formation and flows), (3) Magneto-hydrodynamic (MHD) waves in prominences and (4) the formation and large-scale patterns of the filament channels in which prominences are located. Finally, several outstanding issues in prominence research are discussed, along with observations and models required to resolve them.

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Section: Models Of Prominence Magnetic Structurementioning

confidence: 99%

Section: Evaporation-condensation Modelsmentioning

confidence: 99%

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

et al. 2010

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“…A few remarks can be made about this finding. Retraction of magnetic flux from the lower atmosphere toward the convection zone on a variety of length-scales has been discussed in the literature in connection with flux cancellation events and, more generally, with the general flux budget of the solar surface (see, e.g., the observational results of Chae et al 2004;Kubo & Shimizu 2007;Harvey et al 1999 and the theoretical discussions of Zwaan 1987;Priest 1987;Spruit et al 1987;Cheung et al 2008;Ryutova et al 2003). Different scenarios have been proposed to explain these events.…”

Section: The Formation Of Twisted Tubes Below Granular Downflowsmentioning

confidence: 99%

Magnetic flux emergence into the solar photosphere and chromosphere

Tortosa-Andreu¹,

Moreno‐Insertis

2009

A&A

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Aims. We model the emergence of magnetized plasma across granular convection cells and the low atmosphere, including layers up to the mid-chromosphere. Methods. Three-dimensional numerical experiments are carried out in which the equations of MHD and radiative transfer are solved self-consistently. We use the MURaM code, which assumes local thermodynamic equilibrium between plasma and radiation. Results. In the photosphere, we find good agreement between our simulation predictions and observational results obtained with the Hinode satellite for the velocity and magnetic fields. We also confirm earlier simulation results by other authors. Our experiments reveal a natural mechanism of formation of twisted magnetic flux tubes that results from the retraction of photospheric horizontal fields at new intergranular lanes in decaying granules. In the chromosphere, we present evidence for the non-radiative heating of the emerging magnetized plasma due to the passage of shocks and/or ohmic dissipation. We study the formation of high-temperature points in the magnetic domain. We detect two types of points, classified according to whether they have a photospheric counterpart or otherwise. We also find evidence of those two types in Hinode observations. Using Lagrangian tracing of a large statistical sample of fluid particles, we detect and study episodes of convective collapse of magnetic elements returning to the photosphere. On the other hand, we study the maximum heights reached by all tracers, magnetized or otherwise. Only a small fraction (1.3%) of the magnetic elements reach the mid-chromosphere (z > 750 km), while virtually no unmagnetized elements in the sample rise above the level of the reverse granulation (a few 100 km above the photosphere). We find that the rise into the chromosphere occurs in the form of successive jumps with intermediate stops rather than in a smooth continuous fashion and propose a tentative explanation of this behavior. Finally, also using Lagrange tracing, we document the creation of hightemperature points in the chromosphere via rising shock fronts.

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“…It is associated with the submergence of small scale loops, which have a small radius of curvature and can be pulled under the photosphere by the magnetic tension force (Harvey et al 1999). These small loops are likely to be the product of magnetic reconnection which sets in as the opposite polarity fragments collide (Zwaan 1987;van Ballegooijen & Martens 1989).…”

Section: Introductionmentioning

confidence: 99%

Photospheric flux cancellation and associated flux rope formation and eruption

Green

Kliem

Wallace

2010

A&A

207

241

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Aims. We study an evolving bipolar active region that exhibits flux cancellation at the internal polarity inversion line, the formation of a soft X-ray sigmoid along the inversion line and a coronal mass ejection. The aim is to investigate the quantity of flux cancellation that is involved in flux rope formation in the time period leading up to the eruption. Methods. The active region is studied using its extreme ultraviolet and soft X-ray emissions as it evolves from a sheared arcade to flux rope configuration. The evolution of the photospheric magnetic field is described and used to estimate how much flux is reconnected into the flux rope. Results. About one third of the active region flux cancels at the internal polarity inversion line in the 2.5 days leading up to the eruption. In this period, the coronal structure evolves from a weakly to a highly sheared arcade and then to a sigmoid that crosses the inversion line in the inverse direction. These properties suggest that a flux rope has formed prior to the eruption. The amount of cancellation implies that up to 60% of the active region flux could be in the body of the flux rope. We point out that only part of the cancellation contributes to the flux in the rope if the arcade is only weakly sheared, as in the first part of the evolution. This reduces the estimated flux in the rope to ∼30% or less of the active region flux. We suggest that the remaining discrepancy between our estimate and the limiting value of ∼10% of the active region flux, obtained previously by the flux rope insertion method, results from the incomplete coherence of the flux rope, due to nonuniform cancellation along the polarity inversion line. A hot linear feature is observed in the active region which rises as part of the eruption and then likely traces out the field lines close to the axis of the flux rope. The flux cancellation and changing magnetic connections at one end of this feature suggest that the flux rope reaches coherence by reconnection immediately before and early in the impulsive phase of the associated flare. The sigmoid is destroyed in the eruption but reforms quickly, with the amount of cancellation involved being much smaller than in the course of its original formation.

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Cited by 67 publications

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Physics of Solar Prominences: II—Magnetic Structure and Dynamics

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

Magnetic flux emergence into the solar photosphere and chromosphere

Photospheric flux cancellation and associated flux rope formation and eruption

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