The magnetic nature of wide EUV filament channels and their role in the mass loading of CMEs

Aulanier, G.; Schmieder, B.

doi:10.1051/0004-6361:20020179

Cited by 92 publications

(86 citation statements)

References 41 publications

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“…One of them is that the transition region below the filament is less emissive than the transition region surrounding the filament ). This hypothesis has been supported by extrapolation works showing that field lines supporting the Hα filament may be attracted by parasitic polarities located far away from the PIL (Aulanier & Schmieder 2002). They could form the lateral extensions of the EUV filament.…”

Section: Velocity Vectors and Corks Distribution In The Filament Channelmentioning

confidence: 72%

“…The lateral extensions of the EUV filament are in different locations than the Hα feet. MHD flux tube models suggest that the lateral extensions are due to the attraction of the field lines of the tube by external parasitic polarities (Aulanier & Schmieder 2002). They could be related to different cork accumulation regions, which are away from the main polarity inversion line (PIL), therefore canceling flux related to formation or eruption of filaments would not be along the PIL but at the edges of EUV filament channels.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…The lateral extensions on the northern edge are located in the low atmosphere and may be related directly to the photosphere if we adopt the MHD model of Aulanier & Schmieder (2002). The second component consists of the intermittent brightenings occurring along threads parallel to the filament axis.…”

Section: Filament Activitymentioning

confidence: 99%

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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: Velocity Vectors and Corks Distribution In The Filament Channelmentioning

confidence: 72%

Section: Conclusion and Discussionmentioning

confidence: 99%

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Proper horizontal photospheric flows in a filament channel

Schmieder

Roudier

Mein

et al. 2014

A&A

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“…These feet connect filament bodies suspended in the corona to the lower atmospheric layers. Are these feet formed by continuously injected plasma condensation in magnetic arcades, as hinted by some observations and conceptual models (Martin 1998), or do they consist of quasi-static condensations that are maintained against free-fall by the Lorentz force in a low-lying continuous distribution of magnetic hammocks, from the feet ends to up to the filament bodies, as first predicted by linear force-free field and magnetohydrostatic models (Aulanier & Démoulin 1998, Aulanier & Schmieder 2002, Dudik et al 2008? This debate had been lacking of new discriminators for about ten years, until this issue was recently addressed through new direct measurements of the photospheric magnetic field vector B in a filament channel located far from the center of the solar disc, resulting from the PCA-based inversion of high-precision spectropolarimetric observations with the MTR instrument of the THEMIS telescope (López Ariste et al 2006).…”

Section: Resolution Of the 180 Degree Of Ambiguity And Observations Omentioning

confidence: 96%

Solar prominences

Schmieder¹,

Aulanier²,

Török³

2008

Proc. IAU

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Abstract. Solar filaments (or prominences) are magnetic structures in the corona. They can be represented by twisted flux ropes in a bipolar magnetic environment. In such models, the dipped field lines of the flux rope carry the filament material and parasitic polarities in the filament channel are responsible for the existence of the lateral feet of prominences.Very simple laws do exist for the chirality of filaments, the so-called "filament chirality rules": commonly dextral/sinistral filaments corresponding to left-(resp. right) hand magnetic twists are in the North/South hemisphere. Combining these rules with 3D weakly twisted flux tube models, the sign of the magnetic helicity in several filaments were identified. These rules were also applied to the 180• disambiguation of the direction of the photospheric transverse magnetic field around filaments using THEMIS vector magnetograph data (López Ariste et al. 2006). Consequently, an unprecedented evidence of horizontal magnetic support in filament feet has been observed, as predicted by former magnetostatic and recent MHD models.The second part of this review concerns the role of emerging flux in the vicinity of filament channels. It has been suggested that magnetic reconnection between the emerging flux and the pre-existing coronal field can trigger filament eruptions and CMEs. For a particular event, observed with Hinode/XRT, we observe signatures of such a reconnection, but no eruption of the filament. We present a 3D numerical simulation of emerging flux in the vicinity of a flux rope which was performed to reproduce this event and we briefly discuss, based on the simulation results, why the filament did not erupt.

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“…More realistic models were developped by Aulanier & Démoulin (1998 and Aulanier & Schmieder (2002). They studied periodic configurations and assumed a sufficiently large number of "parasitic" polarities.…”

Section: Dips In Force-free Fieldsmentioning

confidence: 99%

Is the magnetic field in quiescent prominences force-free?

Anzer¹,

Heinzel

2007

A&A

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Aims. We describe under which conditions the magnetic fields of quiescent prominences are force-free and under which gravity plays the dominant role. Methods. The existing observational determinations of the magnetic field are summarised and the calculation of the plasma β is outlined. We derive the dependence of β on the prominence weight and the field strength. Results. We show that in many cases of well-developed quiescent prominences the field can deviate substantially from the force-free situation and gravity fully determines the structure of the magnetic dips.

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The magnetic nature of wide EUV filament channels and their role in the mass loading of CMEs

Cited by 92 publications

References 41 publications

Proper horizontal photospheric flows in a filament channel

Proper horizontal photospheric flows in a filament channel

Solar prominences

Is the magnetic field in quiescent prominences force-free?

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