Counter-streaming gas flows in solar prominences as evidence for vertical magnetic fields

Zirker, J. B.; Engvold, O.; Martin, Sara

doi:10.1038/24798

Cited by 241 publications

(228 citation statements)

References 9 publications

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“…On the other hand high-cadence instrumentation with high-resolution have made a breakthrough in the nature of the dynamics of filament fine-structures. Noneruptive filaments show counter-streaming flows along the fine structures and up-and-down flows in the filament-end ( (Zirker, Engvold, and Martin(1998)), (Lin et al(2005), ), (Berger et al(2008), )). These velocities are lower than 10 km s −1 .…”

Section: Discussionmentioning

confidence: 99%

3D Evolution of a Filament Disappearance Event Observed by STEREO

Gosain

Schmieder²,

Venkatakrishnan³

et al. 2009

Sol Phys

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A filament disappearance event was observed on 22 May 2008 during our recent campaign JOP 178. The filament, situated in the southern hemisphere, showed sinistral chirality consistent with the hemispheric rule. The event was well observed by several observatories in particular by THEMIS. One day before the disappearance, Hα observations showed up and down flows in adjacent locations along the filament, which suggest plasma motions along twisted flux rope. THEMIS and GONG observations show shearing photospheric motions leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with separation angle 52.4 degrees, showed quite different views of this untwisting flux rope in He II 304Å images. Here, we reconstruct the 3D geometry of the filament during its eruption phase using STEREO EUV He II 304Å images and find that the filament was highly inclined to the solar normal. The He II 304Å movies show individual threads, which oscillate and rise to an altitude of about 120 Mm with apparent velocities of about 100 km s −1 , during the rapid evolution phase. Finally, as the flux rope expands into the corona, the filament disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning of the disappearance phase at 02:00 UT, which could be due to partial filament eruption. Further, STEREO Fe XII 195Å images showed bright loops beneath the filament prior to the disappearance phase, suggesting magnetic reconnection below the flux rope.

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Section: Discussionmentioning

confidence: 99%

3D Evolution of a Filament Disappearance Event Observed by STEREO

Gosain

Schmieder²,

Venkatakrishnan³

et al. 2009

Sol Phys

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“…The disappearance and reappearance of a part of a filament has been directly related to emergence of magnetic flux, followed by canceling flux . Zirker et al (1998a) observed counter-streaming of plasma in a quiescent filament (see section 4, Paper I). Using observations at three wavelengths in the Hα line, they found evidence that matter flows along the spine of the filament in both directions.…”

Section: Filament Barbsmentioning

confidence: 99%

“…2. Prominence plasma is predominantly dynamic, exhibiting horizontal and/or vertical motions of order 10-70 km s −1 (Kubota and Uesugi, 1986;Zirker et al, 1998a;Kucera et al, 2003;Lin et al, 2003;Okamoto et al, 2007;Chae et al, 2008). Quiescent filaments can go through phases of enhanced internal motion and activity (Martin, 1973;Tandberg-Hanssen, 1995;Kucera et al, 2006), altering the amount of cool material in the filament (Kilper et al, 2009).…”

Section: Plasma Structure and Dynamicsmentioning

confidence: 99%

“…Therefore, the observed flow direction can be used to infer the direction of the magnetic field, which may help resolve the question whether the magnetic fields in barbs are inclined or horizontal. Zirker et al (1998a) propose that a filament barb consists of a set of closely spaced flow channels that are highly inclined with respect to the vertical direction, with some channels having up-flows and others having downflow. The velocities involved are 5 to 10 km/s, much less than the free-fall velocity corresponding to the filament height.…”

Section: Filament Barbsmentioning

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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“…In these structures, some possible asymmetries may be due to the action of the Coriolis force or to a remnant longitudinal motion in the original mechanical equilibrium which leads to counterflows, but this does not seem the case. Another interpretation of such countermotions involves mass flow along field lines which bend down, as proposed in a different context by Zirker et al (1998).…”

Section: Discussionmentioning

confidence: 99%

High-Resolution Observations of Siphon Flows in a Solar Magnetic Pore

Guglielmino

Zuccarello

2011

ApJ

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We investigate signatures of siphon flows in a region around a solar magnetic pore, observed in the photosphere at μ = 0.6, during its decay phase. We analyze high-resolution Stokes spectra acquired by Hinode/Solar Optical Telescope along the Fe i pair at 630.2 nm. We determine the vector magnetic field and the line-of-sight velocity by an inversion of the full Stokes vector using the SIR code. We also analyze photospheric G-band filtergrams. We find evidence of a transient siphon (counter)flow at the edge of the pore. An arch-shaped structure is found to have upflow motions of 4 km s −1 in the footpoint with a stronger magnetic field and positive polarity, and downflows of the same order of magnitude in the footpoint with opposite polarity and a weaker magnetic field. The event is different from those reported in previous observations of the Sun's atmosphere and may represent a physical constraint for numerical models.

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Counter-streaming gas flows in solar prominences as evidence for vertical magnetic fields

Cited by 241 publications

References 9 publications

3D Evolution of a Filament Disappearance Event Observed by STEREO

3D Evolution of a Filament Disappearance Event Observed by STEREO

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

High-Resolution Observations of Siphon Flows in a Solar Magnetic Pore

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