Photospheric flows around a quiescent filament

Rondi, S.; Roudier, Th.; Molodij, G.; Bommier, V.; Keil, S. L.; Sütterlin, P.; Malherbe, Jean-Marie; Meunier, N.; Schmieder, B.; Maloney, Philip R.

doi:10.1051/0004-6361:20066649

Cited by 22 publications

(20 citation statements)

References 23 publications

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“…One proposed cause of such alignment is in the relative motion of the photospheric fibril footpoints in the two different polarities (e.g., Wang and Muglach, 2007). Photospheric flux convergence is often caused by supergranular divergence motions at the sides and across the PIL (e.g., Rondi et al, 2007). Both cases studied by Wang and Muglach (2007) exhibited convergence toward the neutral line, but in the first case there was also parallel motion, while it was anti-parallel in the second case.…”

Section: Discussionmentioning

confidence: 99%

“…The presence of sporadic minor polarity concentrations around the PIL has also been considered important for filament formation. Rondi et al (2007) claim that the converging motions may transport these small scale polarities across the PIL, thus forming the parasitic polarities in which filament barbs are thought to be rooted. They identified this process as causing the formation of the filament barbs, as supported by other observations (e.g., Schmieder et al, 2006) and modeling (e.g., Aulanier and Schmieder, 2002).…”

Section: Living Reviews In Solar Physicsmentioning

confidence: 99%

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Solar Prominences: Observations

Parenti

2014

Living Rev. Solar Phys.

290

234

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Solar prominences are one of the most common features of the solar atmosphere. They are found in the corona but they are one hundred times cooler and denser than the coronal material, indicating that they are thermally and pressure isolated from the surrounding environment. Because of these properties they appear at the limb as bright features when observed in the optical or the EUV cool lines. On the disk they appear darker than their background, indicating the presence of a plasma absorption process (in this case they are called filaments). Prominence plasma is embedded in a magnetic environment that lies above magnetic inversion lines, denoted a filament channel.This paper aims at providing the reader with the main elements that characterize these peculiar structures, the prominences and their environment, as deduced from observations. The aim is also to point out and discuss open questions on prominence existence, stability and disappearance.The review starts with a general introduction of these features and the instruments used for their observation. Section 2 presents the large scale properties, including filament morphology, thermodynamical parameters, magnetic fields, and the properties of the surrounding coronal cavity, all in stable conditions. Section 3 is dedicated to small-scale observational properties, from both the morphological and dynamical points of view. Section 4 introduces observational aspects during prominence formation, while Section 5 reviews the sources of instability leading to prominence disappearance or eruption. Conclusions and perspectives are given in Section 6.

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Section: Discussionmentioning

confidence: 99%

Section: Living Reviews In Solar Physicsmentioning

confidence: 99%

Solar Prominences: Observations

Parenti

2014

Living Rev. Solar Phys.

290

234

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“…Photospheric converging or shearing flows may be detected by local correlation tracking (cf. Magara, 1999;Rondi et al, 2007;. For some surface models diffusion of flux towards a PIL with subsequent cancellation plays the role of the converging flow.…”

Section: Theoretical Models Of Filament Formationmentioning

confidence: 99%

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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“…They found a pattern in the large scale horizontal flows at the solar surface that interacts with the differential rotation. The local photospheric flows were also measured with a higher spatial resolution (0.5 arcsec) in the filament channel during its eruption phase using TRACE 1600 Å to show the coupling between convection and magnetic field (Rondi et al 2007). It was shown that the disappearance of the filament originates in a filament gap.…”

Section: Introductionmentioning

confidence: 99%

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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Photospheric flows around a quiescent filament

Cited by 22 publications

References 23 publications

Solar Prominences: Observations

Solar Prominences: Observations

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

Proper horizontal photospheric flows in a filament channel

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