3-D magnetic configurations for filaments and flares: The role of “magnetic dips” and “bald patches”

Aulanier, G.; Schmieder, B.; Driel‐Gesztelyi, L. van; Kucera, T. A.; Démoulin, P.; Fang, Cheng; Mein, N.; Vial, J. C.; Mein, P.; Tang, Yuhua; DeForest, C. E.

doi:10.1016/s0273-1177(99)01100-x

Cited by 32 publications

(55 citation statements)

References 4 publications

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“…Assuming that the MDI is reliable enough for such extended weak fields, we fully confirm our previous results on the interpretation of filament feet in terms of magnetic dips located underneath and next to the filament (Aulanier & Démoulin 1998), their association with photospheric parasitic polarities (as observed by Martin 1990) and their location on the edge of these polarities (as observed by Aulanier et al 1998b;Wang 2001).…”

Section: Location and Magnetic Field Of Filament Feetsupporting

confidence: 90%

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

Aulanier¹,

Schmieder²

2002

A&A

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Abstract.Previous works have shown that dark and wide EUV filament channels observed at λ < 912Å are due to absorption of EUV lines in cool plasma condensations that are not observed in Hα. We extend this interpretation and we address the issue of the possible injection of their mass into CMEs, through the magneto-hydrostatic modeling in 3D of one filament observed both in Hα and in EUV. The model parameters are fixed so as to match the Hα observations only. Further comparison of the model with the EUV observations reveal the magnetic nature of the absorbing plasma condensations. They are formed in magnetic dips, as for the filament itself. Opacity ratios and the hydrostatic condition imply that the dips must be filled by cool material up to 1700 km, which increases the filament mass by 50% as compared to Hα estimations. Far from the filament, the absorbing condensations are located below 4 Mm in altitude above the photosphere, on the edge of weak photospheric parasitic polarities, within the lower parts of long field lines overlaying the filament. By physical analogy with Hα filament feet, we redefined these extended regions as EUV feet. The broadening of the EUV filament channel is dominated by EUV feet, while the larger filling of dips plays a non-negligible but minor role. Further implications from this work are discussed, on the visibility and the geometry of the condensations, on the existence of EUV filament channels in the absence of filaments, on the loading of cool material into filament feet through bald patch reconnection and on the complex geometry of the upper prominence-corona transition region. The magnetic topology implies that during the filament eruption, the mass of its wide EUV feet will not contribute to the CME, whereas the extra mass provided by the large filling of dips in the filament flux tube will be loaded into the CME.

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Section: Location and Magnetic Field Of Filament Feetsupporting

confidence: 90%

“…Direct representation of the computed topology is difficult since it involves a combination of large and small scales, so we refer the reader to Bungey et al (1996) and to Aulanier et al (1998b (Figs. 2a and 6a)) where this topology was calculated for theoretical models.…”

Section: Topology Of the Magnetic Fieldmentioning

confidence: 99%

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

Aulanier¹,

Schmieder²

2002

A&A

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“…3e in Dudík et al 2008). Aulanier et al (1998b) explain very well by means of their magnetic extrapolation the relationship between parasitic polarities and the flux tube itself and their evolution. The flux of parasitic polarity should overcome that of the twisted flux tube and destroy the twisted configuration.…”

Section: Discussionmentioning

confidence: 71%

“…The barbs are piled-up dips touching the photosphere. When a parasitic polarity is canceled or moves, the feet move and can even disappear (Aulanier et al 1998b;Schmieder et al 2006;Gosain et al 2009). In this 3D perspective, the prominence material should be trapped within inclined field lines and the downflow motion should occur along the shallow dips.…”

Section: Discussionmentioning

confidence: 99%

Velocity vectors of a quiescent prominence observed byHinode/SOT and the MSDP (Meudon)

Schmieder¹,

Chandra²,

Berlicki

et al. 2010

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Context. The dynamics of prominence fine structures present a challenge to our understanding of the formation of cool plasma prominence embedded in the hot corona. Aims. Observations performed by the high resolution Hinode/SOT telescope allow us to compute velocities perpendicular to the lineof-sight or transverse velocities. Combining simultaneous observations obtained in Hα with Hinode/SOT and the MSDP spectrograph operating in the Meudon solar tower, we derive the velocity vectors of a quiescent prominence. Methods. The velocities perpendicular to the line-of-sight are measured using a time-slice technique and the Doppler shifts velocity using the bisector method.Results. The Doppler shifts of bright threads derived from the MSDP show counterstreaming of the order of 5 km s −1 in the prominence and reaching 15 km s −1 at the edges of the prominence. Even though they are minimum values because of seeing effects, they are of the same order as the transverse velocities. Conclusions. These measurements are very important because they suggest that the vertical structures detected by SOT may not be true vertical magnetic structures in the sky plane. The vertical structures could be a pile up of dips in more or less horizontal magnetic field lines in a 3D perspective, as proposed by many MHD modelers. In our analysis, we also calibrate the Hinode Hα data using MSDP observations obtained simultaneously.

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“…The extrapolation with such LFFF models from a photospheric manetogram has been shown to explain many of the observed features of filaments (see, e.g., Aulanier & Demoulin 1998;Aulanier et al 2000). The force-free parameter α in LFFF models has been computed by comparing extrapolated magnetic field lines with coronal EUV-images (e.g.…”

Section: Introductionmentioning

confidence: 99%

A first step in reconstructing the solar corona self-consistently with a magnetohydrostatic model during solar activity minimum

Ruan¹,

Wiegelmann²,

Inhester³

et al. 2008

A&A

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Aims. We compute the distribution of the magnetic field and the plasma in the global corona with a self-consistent magnetohydrostatic (MHS) model. Methods. Because direct measurements of the solar coronal magnetic field and plasma are extremely difficult and inaccurate, we use a modeling approach based on observational quantities, e.g. the measured photospheric magnetic field, to reconstruct the structure of the global solar corona. We take an analytic magnetohydrostatic model to extrapolate the magnetic field in the corona from photospheric magnetic field measurement. In the model, the electric current density can be decomposed into two components: one component is aligned with the magnetic field lines, whereas the other component flows in spherical shells. The second component of the current produces finite Lorentz forces that are balanced by the pressure gradient and the gravity force. We derive the 3D distribution of the magnetic field and plasma self-consistently in one model. The boundary conditions are given by a synoptic magnetogram on the inner boundary and by a source surface model at the outer boundary. Results. The density in the model is higher in the equatorial plane than in the polar region. We compare the magnetic field distribution of our model with potential and force-free field models for the same boundary conditions and find that our model differs noticeably from both. We discuss how to apply the model and how to improve it.

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3-D magnetic configurations for filaments and flares: The role of “magnetic dips” and “bald patches”

Cited by 32 publications

References 4 publications

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

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

Velocity vectors of a quiescent prominence observed byHinode/SOT and the MSDP (Meudon)

A first step in reconstructing the solar corona self-consistently with a magnetohydrostatic model during solar activity minimum

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