The fine structure of prominences

Engvold, O.

doi:10.1007/bf00162453

Cited by 132 publications

(53 citation statements)

References 19 publications

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“…While some theoretical models consider prominences as an infinite slab of plasma having a small thickness, many observations of quiescent prominences show very fine structures in the body of the filament, suggesting that they are composed of small-scale threads. The existence of this internal structure in prominences was already suggested by Menzel & Evans (1953) and was clarified with the improvement of observational capabilities (Engvold 1976;Engvold et al 1987). Although vertical filamentary structures can be seen in limb prominences (Dunn 1960), there is also evidence for the existence of horizontal fine structures within prominences (Schmieder & Mein 1989;Schmieder et al 1991).…”

Section: Introductionmentioning

confidence: 67%

Fast MHD oscillations in prominence fine structures

Díaz¹,

Oliver²,

Erdélyi³

et al. 2001

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Abstract. High-resolution observations suggest that quiescent solar prominences are made of small-scale fibrils stacked one after another in both the vertical and horizontal directions. These fibrils are interpreted as the cool, highermost part of much larger coronal loops which are rooted in the solar photosphere. On the other hand, there is some evidence showing that small amplitude oscillations in prominences can affect individual or groups of fibrils, which vibrate with their own periods. Using a simple magnetostatic model to represent the fibril structure of quiescent solar prominences, Joarder et al. (1997) investigated some oscillatory properties of the Alfvén and fast magnetohydrodynamic modes. In this paper, with a proper treatment of boundary conditions, we reexamine their configuration and explore more deeply the basic features (mainly frequency and spatial structure) of the fast mode. The main conclusion is that, for reasonable values of the fibril's width, perturbations extend far away from its axis and, therefore, a single oscillating fibril can excite oscillations in neighbouring ones.

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Section: Introductionmentioning

confidence: 67%

Fast MHD oscillations in prominence fine structures

Díaz¹,

Oliver²,

Erdélyi³

et al. 2001

A&A

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“…5. Many authors have observed the presence of threads in filaments and prominences before (e.g., Menzel & Wolbach 1960;Engvold 1976;Lin et al 2005Lin et al , 2008Okamoto et al 2007). It is generally believed that dark thin features in the chromosphere near ARs trace magnetic field lines.…”

Section: Tip-ii Observationsmentioning

confidence: 99%

An active region filament studied simultaneously in the chromosphere and photosphere

Kuckein

Pillet

Centeno

2012

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Aims. A thorough multiwavelength, multiheight study of the vector magnetic field in a compact active region filament (NOAA 10781) on 2005 July 3 and 5 is presented. We suggest an evolutionary scenario for this filament. Methods. Two different inversion codes were used to analyze the full Stokes vectors acquired with the Tenerife Infrared Polarimeter (TIP-II) in a spectral range that comprises the chromospheric He i 10 830 Å multiplet and the photospheric Si i 10 827 Å line. In addition, we used SOHO/MDI magnetograms, as well as BBSO and TRACE images, to study the evolution of the filament and its active region (AR). High-resolution images of the Dutch Open Telescope were also used.Results. An active region filament (formed before our observing run) was detected in the chromospheric helium absorption images on July 3. The chromospheric vector magnetic field in this portion of the filament was strongly sheared (parallel to the filament axis), whereas the photospheric field lines underneath had an inverse polarity configuration. From July 3 to July 5, an opening and closing of the polarities on either side of the polarity inversion line (PIL) was recorded, resembling the recently discovered process of the sliding door effect seen by Hinode. This is confirmed with both TIP-II and SOHO/MDI data. During this time, a newly created region that contained pores and orphan penumbrae at the PIL was observed. On July 5, a normal polarity configuration was inferred from the chromospheric spectra, while strongly sheared field lines aligned with the PIL were found in the photosphere. In this same data set, the spine of the filament is also observed in a different portion of the field of view and is clearly mapped by the silicon line core. Conclusions. The inferred vector magnetic fields of the filament suggest a flux rope topology. Furthermore, the observations indicate that the filament is divided in two parts, one which lies in the chromosphere and another one that stays trapped in the photosphere. Therefore, only the top of the helical structure is seen by the helium lines. The pores and orphan penumbrae at the PIL appear to be the photospheric counterpart of the extremely low-lying filament. We suggest that orphan penumbrae are formed in very narrow PILs of compact ARs and are the photospheric manifestation of flux ropes in the photosphere.

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“…The overall structure of quiescent prominences changes little with time, preserving their shape during days and even weeks. Locally, they consist of fine and vertically oriented plasma structures, so-called threads, that evolve continually (e.g., Engvold 1976;Zirker et al 1994). Recent ob-A movie is available in electronic form at http://www.aanda.org 1 There are many papers about solar prominences, but we recommend that the reader first go through the historical work of Einar Tandberg-Hanssen (e.g., Tandberg-Hanssen 1998, 2011 servations taken with the Hinode satellite have revolutionized our knowledge of the fine-scale structuring and dynamics of quiescent prominences; for instance, plasma oscillations, supersonic downflows, or plasma instabilities like the Rayleigh-Taylor instability in prominence bubbles (Berger et al 2008(Berger et al , 2010Chae et al 2008;Okamoto et al 2007).…”

Section: Introductionmentioning

confidence: 99%

The magnetic field configuration of a solar prominence inferred from spectropolarimetric observations in the He i 10 830 Å triplet

Suárez

Ramos

Bueno

2014

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Context. Determining the magnetic field vector in quiescent solar prominences is possible by interpreting the Hanle and Zeeman effects in spectral lines. However, observational measurements are scarce and lack high spatial resolution. Aims. We determine the magnetic field vector configuration along a quiescent solar prominence by interpreting spectropolarimetric Results. For the most probable magnetic field vector configuration, the analysis depicts a mean field strength of 7 gauss. We do not find local variations in the field strength except that the field is, on average, lower in the prominence body than in the prominence feet, where the field strength reaches ∼25 gauss. The averaged magnetic field inclination with respect to the local vertical is ∼77 • . The acute angle of the magnetic field vector with the prominence main axis is 24 • for the sinistral chirality case and 58 • for the dextral chirality. These inferences are in rough agreement with previous results obtained from the analysis of data acquired with lower spatial resolutions.

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The fine structure of prominences

Cited by 132 publications

References 19 publications

Fast MHD oscillations in prominence fine structures

Fast MHD oscillations in prominence fine structures

An active region filament studied simultaneously in the chromosphere and photosphere

The magnetic field configuration of a solar prominence inferred from spectropolarimetric observations in the He i 10 830 Å triplet

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