Solar prominences with Na and Mg emissions  
 and centrally reversed Balmer lines

Stellmacher, G.; Wiehr, E.

doi:10.1051/0004-6361:20041550

Cited by 9 publications

(8 citation statements)

References 9 publications

(32 reference statements)

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“…These are mostly quiescent prominences, in bright quiescent prominences the ratio can go up to 10 %. These results are consistent with the work of Stellmacher and Wiehr (2005) who got similar results for the Na i D 2 line. Only in a few cases ratio between Na i D 1 and He i D 3 or Na i D 2 and He i D 3 can be larger than 20 %.…”

Section: Contamination With Na I D 1 and D 2 Lines And Comet Detectionsupporting

confidence: 93%

Visibility of Prominences Using the He i D3 Line Filter on the PROBA-3/ASPIICS Coronagraph

Jejčič¹,

Heinzel²,

Labrosse³

et al. 2018

Sol Phys

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We determine an optimal width and shape of the narrow-band filter centered around the He i D 3 line for prominence and coronal mass ejection (CME) observations with the ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun) coronagraph onboard the PROBA-3 (Project for On-board Autonomy) satellite, to be launched in 2020. We analyze He i D 3 line intensities for three representative non-LTE prominence models at temperatures 8, 30 and 100 kK computed by the radiative transfer code and the prominence visible-light (VL) emission due to Thomson scattering on the prominence electrons. We compute various useful relations at prominence lineof-sight (LOS) velocities of 0, 100, and 300 km s −1 for 20Å wide flat filter and three Gaussian filters with full width at half maximum (FWHM) equal to 5, 10, and 20Å to show the relative brightness contribution of the He i D 3 line and the prominence VL to the visibility in a given narrow-band filter. We also discuss possible signal contamination by Na i D 1 and D 2 lines which otherwise may be useful to detect comets. Results mainly show: i) an optimal narrow-band filter should be flat or somewhere between flat and Gaussian with FWHM of 20Å in order to detect fast moving prominence structures, ii) the maximum emission in the He i D 3 line is at 30 kK and the minimal at 100 kK, and iii) the ratio of

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Section: Contamination With Na I D 1 and D 2 Lines And Comet Detectionsupporting

confidence: 93%

Visibility of Prominences Using the He i D3 Line Filter on the PROBA-3/ASPIICS Coronagraph

Jejčič¹,

Heinzel²,

Labrosse³

et al. 2018

Sol Phys

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“…4 in Stellmacher & Wiehr 2000), and from spectra with THEMIS ( Fig. 3a in Stellmacher & Wiehr 2005). That relation (shown in Wiehr & Stellmacher 2015) is at best represented by the GHV models with T kin = 4300 K and T kin = 6000 K (both V nth = 5 km s −1 ) Gunár et al (2012) use 2D multi-thread models with prominence-corona transition region, PCTR, to reproduce observed Hα radiances and widths, and deduce similar low temperatures down to T kin ≈ 5000 K.…”

Section: T Kin From Line Radiancesmentioning

confidence: 99%

Non-thermal line-broadening in solar prominences

Stellmacher

Wiehr

2015

A&A

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Aims. We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities. Methods. We have simultaneously observed a wide range of optically thin lines in quiescent prominences, selected for bright and narrow Mg b emission without line satellites from macro-shifts. Results. We find a ratio of reduced widths, Δλ D /λ 0 , of Hγ and Hδ of 1.05 ± 0.03, which can hardly be attributed to saturation, since both are optically thin for the prominences observed: τ γ ≤ 0.3, τ δ ≤ 0.15. We confirm the ratio of reduced widths of He 4772 (triplet) and He 5015 (singlet) of 1.1 ± 0.05 at higher significance and detect a width ratio of Mg b 2 and Mg 4571 (both from the triplet system) of 1.3 ± 0.1. Conclusions. The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [T kin ; V nth ]. Values of T kin deduced from observed line radiances using models indicate low temperatures down to T kin ≈ 5000 K. Non-thermal velocities, related to different physical states of the respective emitting prominence region, seem to be the most important line broadening mechanism.

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“…Such emissions should occur in prominences with negligible macro-velocities and low non-thermal line broadening, which are known to be bright in Hα though with a low He-to-Balmer ratio (Engvold and Livingston, 1971;Stellmacher and Wiehr, 1995). Such prominences show significant Na D and Mg b emission and saturated Hα (and even Hβ) profiles but did so far not allow a He ii 4685.7 Å line profile analysis (Stellmacher and Wiehr, 2005).…”

Section: Introductionmentioning

confidence: 99%

Helium Emissions Observed in Ground-Based Spectra of Solar Prominences

Ramelli

Stellmacher

Wiehr³

et al. 2012

Sol Phys

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The only prominent line of singly ionized helium in the visible spectral range, He II 4686 Å, is observed together with the He I 5015 Å singlet and the He I 4471 Å triplet line in solar prominences. The Na D 2 emission is used as a tracer for He II emissions which are sufficiently bright to exceed the noise level near 10 −6 of the disk-center intensity. The prominences thus selected are characterized by small non-thermal line broadening and almost absent velocity shifts, yielding narrow line profiles without wiggles. The reduced widths [ λ D /λ] of He II 4686 Å are 1.5 times broader than those of the He I 4471 Å triplet and 1.65 times broader than those of the He I 5015 Å singlet. This indicates that the He lines originate in a prominence-corona transition region with outwards increasing temperature.

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Solar prominences with Na and Mg emissions and centrally reversed Balmer lines

Cited by 9 publications

References 9 publications

Visibility of Prominences Using the He i D3 Line Filter on the PROBA-3/ASPIICS Coronagraph

Visibility of Prominences Using the He i D3 Line Filter on the PROBA-3/ASPIICS Coronagraph

Non-thermal line-broadening in solar prominences

Helium Emissions Observed in Ground-Based Spectra of Solar Prominences

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