Eruption of magnetic flux ropes during flux emergence

Archontis, V.; Török, Tibor

doi:10.1051/0004-6361:200811131

Cited by 140 publications

(194 citation statements)

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“…The studied filament in this paper was existing for several rotations. MHD models show that the convection cells are different in flux emergence regions (Archontis & Török 2008;Archontis & Hood 2009). Future studies of the coupling between convection and filaments should be done during filament emergence.…”

Section: Conclusion and Discussionmentioning

confidence: 98%

Proper horizontal photospheric flows in a filament channel

Schmieder

Roudier

Mein

et al. 2014

A&A

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Context. An extended filament in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in Hα with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the Hα threads and bright moving blobs (jets) along the 304 Å filament channel were observed during 10 h before the filament erupted at 17:03 UT. Aims. The aim of the paper is to understand the coupling between magnetic field and convection in filament channels and relate the horizontal photospheric motions to the activity of the filament.Methods. An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the filament channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation. Results. Supergranules are clearly identified in the filament channel. Diverging flows inside the supergranules are similar in and out of the filament channel. Converging flows corresponding to the accumulation of corks are identified well around the Hα filament feet and at the edges of the EUV filament channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s −1 , but with a mean velocity of 0.35 km s −1 . In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity. Conclusions. The coupling between convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its anchorage points with the photosphere, which are magnetized areas (ends, feet, lateral extensions of the EUV filament channel). From a large scale point-of-view, the differential rotation induced a shear of 0.1 km s −1 in the filament. From a small scale point-of-view, any convective motions favored the interaction of the parasitic polarities responsible for the anchorages of the filament to the photosphere with the surrounding network and may explain the activity of the filament.

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Section: Conclusion and Discussionmentioning

confidence: 98%

Proper horizontal photospheric flows in a filament channel

Schmieder

Roudier

Mein

et al. 2014

A&A

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“…Therefore is remains unclear whether such a process may occur. In contrast, many authors have shown that during the process of flux emergence, after the top of the flux rope has emerged, magnetic reconnection or helicity injection (Manchester et al, 2004;Magara, 2006;Archontis and Török, 2008;Fan, 2009) may reconfigure the emerged coronal arcade to produce a secondary coronal flux rope. During the formation of the secondary flux rope the reconnection may then lift cool dense material to coronal heights.…”

Section: Active Region Filamentsmentioning

confidence: 97%

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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“…A key feature in these experiments is the formation of a new flux rope at photospheric/chromospheric heights (Magara & Longcope 2001;Manchester et al 2004;Gibson & Fan 2006;Archontis & Hood 2008), consisting of weakly twisted magnetic field lines surrounding its axis (Archontis & Török 2008;Archontis & Hood 2010). The axis of the new flux rope is distinct from the axis of the original subphotospheric flux tube that initially emerges from the solar interior.…”

Section: Introductionmentioning

confidence: 99%

“…The evolution of the magnetic field after the break-up of the original flux tube into two parts could be considered as "partial-emergence" of the magnetic field (e.g. Manchester et al 2004;Gibson & Fan 2006;MacTaggart & Hood 2009;Archontis & Török 2008). Indeed, the exact location of the internal reconnection with respect to the original axis of the emerging field determines whether all, some (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Previous numerical studies have revealed that the eruption of the new magnetic flux rope depends on the properties of the magnetic environment that it emerges into, such as the relative orientation and the field strength (Archontis & Török 2008;Archontis & Hood 2010). It has been found that if the external, ambient magnetic field declines with height at a sufficiently steep rate, the new flux rope will most likely experience an eruption (Fan 2010).…”

Section: Introductionmentioning

confidence: 99%

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Magnetic flux emergence: a precursor of solar plasma expulsion

Archontis

Hood

2012

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Aims. We model the emergence of magnetized plasma from the top of the convection zone to the lower corona. We investigate the eruption of coronal flux ropes above emerging flux regions. Methods. We performed three-dimensional numerical experiments in which the time-dependent and resistive equations of MHD are solved self-consistently, using the Lare3D code. Results. A subphotospheric magnetic flux tube rises from the convectively unstable layer into the solar surface, followed by the formation and eruption of a new flux rope into the corona. Firstly, we examined the case where the corona is field-free. The expansion of the emerging field forms an envelope sheath that surrounds the newly formed flux rope. The erupting ropes are confined by the envelope field. The eruptions are driven by the gradient of the gas pressure and the tension of fieldlines that reconnect within the emerging flux region. The amount of the initial twist of the emerging field and the dense plasma that is lifted up, determine the heighttime profile of the erupting ropes. Secondly, we examined the case of emergence into a pre-existing magnetic field in the upper solar atmosphere. A variety of different ambient field configurations was used in the experiments. External reconnection between the emerging and the pre-existing field may result in the removal of sufficient flux from the interacting fields and the full ejection of the flux ropes. Conclusions. The results indicate that the relative contact angle of the interacting flux systems and their field strengths are crucial parameters that ultimately affect the evolution of the eruption of the rope into the higher solar atmosphere. One important result is that for any contact angle that favors reconnection, ejective eruptions occur earlier when the ambient field is relatively strong. In many cases, the erupting plasma adopts an S-like configuration. The sigmoidal structure accelerates during the fast eruption of the rope. The acceleration is enhanced by the external and internal reconnection of fieldlines during the rising motion of the rope. A key result is that in the reconnection-favored cases, the flux ropes experience ejective eruptions when the envelope flux is reduced (owing to removal by external reconnection) below that of the erupting flux rope. If the envelope flux stays higher than the erupting flux, the magnetic flux rope remains confined by the envelope field.

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Eruption of magnetic flux ropes during flux emergence

Cited by 140 publications

References 23 publications

Proper horizontal photospheric flows in a filament channel

Proper horizontal photospheric flows in a filament channel

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

Magnetic flux emergence: a precursor of solar plasma expulsion

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