Velocity vectors of a quiescent prominence observed by<i><i>Hinode</i></i>/SOT and the MSDP (Meudon)

Schmieder, B.; Chandra, Ramesh; Berlicki, A.; Mein, P.

doi:10.1051/0004-6361/200913477

Cited by 84 publications

(81 citation statements)

References 34 publications

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“…Schmieder et al (2010) and Berger et al (2010) analyzed A&A 543, A93 (2012) emission-measure curves that are also in good agreement with the observations. More on the modelling of prominences can be found e.g.…”

Section: Introductionsupporting

confidence: 74%

Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

Gunár

Mein

Schmieder

et al. 2012

A&A

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Aims. We analyze the dynamics of the prominence fine structures of a quiescent prominence observed on April 26, 2007 during a coordinated campaign of several spaceborne and ground-based instruments. We use Lyman spectra observed by SOHO/SUMER and the Hα line spectra obtained by MSDP spectrograph working at the Meudon Solar Tower. Methods. We employ the 2D multi-thread prominence fine-structure modelling that includes randomly distributed line-of-sight (LOS) velocities of individual threads to derive models producing synthetic Lyman lines in good agreement with the SOHO/SUMER observations. We then use these models to produce synthetic Hα line spectra that we compare with the observed spectra using three statistical parameters: the line integrated intensity, the line full-width at half-maximum (FWHM), and the Doppler velocity derived from shifts of the line profiles. Results. We demonstrate that the 2D multi-thread models that produce synthetic Lyman spectra in agreement with observations also generate synthetic Hα spectra in good agreement with the observed ones. The statistical analysis of the FWHM and Doppler velocities of the synthetic Hα line profiles show that the overall LOS velocities in the April 26, 2007 prominence at the time of the observations were below 15 km s −1 and in the prominence core were close to 10 km s −1 . In combination with the analysis of the Lyman spectra, we determine several physical parameters of the observed prominence fine-structures that show that the April 26, 2007 prominence had a relatively low-mass weakly magnetized structure. We are also able to impose some constraints on the prominence core temperature, which may be relatively low, with values below 6000 K. Conclusions. The combination of 2D non-LTE prominence fine-structure modelling with the statistical analysis of the observed and synthetic Lyman and Hα spectra allows us to analyze the influence of the model input parameters and the velocity fields on the synthetic Hα line profiles, thus determine the overall dynamics of the observed prominence as well as the physical parameters of its plasma.

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Section: Introductionsupporting

confidence: 74%

Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

Gunár

Mein

Schmieder

et al. 2012

A&A

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“…The interval of ±5 km s −1 , presented in the top right panel of Figure 6, is characteristic for the quiescent type of prominences and is fully in line with He i D3 (Prasad, Ambastha, and Mathew, 1999), Hα (e.g. Schmieder et al, 2010), He i 10 830Å (e.g. Orozco Suárez, Asensio Ramos, and Trujillo Bueno, 2014), and Mg ii k & h (e.g.…”

Section: Spectral Characteristics Of the Double-gaussian Modelsupporting

confidence: 64%

Spectral Characteristics of the He i D3 Line in a Quiescent Prominence Observed by THEMIS

et al. 2017

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We analyze the observations of a quiescent prominence acquired by the Téléscope Heliographique pour l'Étude du Magnetisme et des Instabilités Solaires (THEMIS) in the He i 5876Å (He i D3) multiplet aiming to measure the spectral characteristics of the He i D3 profiles and to find for them an adequate fitting model. The component characteristics of the He i D3 Stokes I profiles are measured by the fitting system approximating them with a double Gaussian. This model yields an He i D3 component peak intensity ratio of 5.5 ± 0.4, which differs from the value of 8 expected in the optically thin limit. Most of the measured Doppler velocities lie in the interval ±5 km s −1 , with a standard deviation of ±1.7 km s −1 around the peak value of 0.4 km s −1 . The wide distribution of the full-width at half maximum has two maxima at 0.25Å and 0.30Å for the He i D3 blue component and two maxima at 0.22Å and 0.31Å for the red component. The width ratio of the components is 1.04 ± 0.18. We show that the double-Gaussian model systematically underestimates the blue wing intensities. To solve this problem, we invoke a two-temperature multiGaussian model, consisting of two double-Gaussians, which provides a better representation of He i D3 that is free of the wing intensity deficit. This model suggests temperatures of 11.5 kK and 91 kK, respectively, for the cool and the hot component of the target prominence. The cool and hot components of a typical He i D3 profile have component peak intensity ratios of 6.6 and 8, implying a prominence geometrical width of 17 Mm and an optical thickness of 0.3 for the cool component, while the optical thickness of the hot component is negligible. These prominence parameters seem to be realistic, suggesting the physical adequacy of the multi-Gaussian model with important implications for interpreting He i D3 spectropolarimetry by current inversion codes.

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“…8). The plasma in the filament threads moves with the magnetic field lines in opposite directions, appearing as "counter-streaming" flows (Zirker et al 1998;Schmieder et al 2010;Alexander et al 2013). The speed of the "counterstreaming" flows is about 5−20 km s −1 , comparable to that of quasi-periodic upflows at the bases of filament threads.…”

Section: Summary and Discussionmentioning

confidence: 99%

Subarcsecond bright points and quasi-periodic upflows below a quiescent filament observed by IRIS

Zhang

2016

A&A

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Context. The new Interface Region Imaging Spectrograph (IRIS) mission provides high-resolution observations of UV spectra and slit-jaw images (SJIs). These data have become available for investigating the dynamic features in the transition region (TR) below the on-disk filaments. Aims. The driver of "counter-streaming" flows along the filament spine is still unknown yet. The magnetic structures and the upflows at the footpoints of the filaments and their relations with the filament mainbody have not been well understood. We study the dynamic evolution at the footpoints of filaments in order to find some clues for solving these questions. Methods. Using UV spectra and SJIs from the IRIS, along with coronal images and magnetograms from the Solar Dynamics Observatory (SDO), we present the new features in a quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic upflows.Results. The BPs in the TR have a spatial scale of about 350−580 km and lifetimes of more than several tens of minutes. They are located at stronger magnetic structures in the filament channel with a magnetic flux of about 10 17 −10 18 Mx. Quasi-periodic brightenings and upflows are observed in the BPs, and the period is about 4−5 min. The BP and the associated jet-like upflow comprise a "tadpole-shaped" structure. The upflows move along bright filament threads, and their directions are almost parallel to the spine of the filament. The upflows initiated from the BPs with opposite polarity magnetic fields have opposite directions. The velocity of the upflows in the plane of sky is about 5−50 km s −1 . The emission line of Si IV 1402.77 Å at the locations of upflows exhibits obvious blueshifts of about 5−30 km s −1 , and the line profile is broadened with the width of more than 20 km s −1 . Conclusions. The BPs seem to be the bases of filament threads, and the upflows are able to convey mass for the dynamic balance of the filament. The "counter-streaming" flows in previous observations may be caused by the propagation of bi-directional upflows initiated from opposite polarity magnetic fields. We suggest that quasi-periodic brightenings of BPs and quasi-periodic upflows result from small-scale oscillatory magnetic reconnections, which are modulated by solar p-mode waves.

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

Cited by 84 publications

References 34 publications

Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

Dynamics of quiescent prominence fine structures analyzed by 2D non-LTE modelling of the Hα line

Spectral Characteristics of the He i D3 Line in a Quiescent Prominence Observed by THEMIS

Subarcsecond bright points and quasi-periodic upflows below a quiescent filament observed by IRIS

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