Magnetic Fields in Prominences: Inversion Techniques for Spectropolarimetric Data of the He<scp>i</scp>D<sub>3</sub>Line

Ariste, Lopez; Casini, R.

doi:10.1086/341260

Cited by 80 publications

(86 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(We recommend a reader of Léger and Paletou (2009) to change their Figure 9 for Figure 7.21 in Léger (2008).) This compatibility of the optical thinness with the ratio of lower than 8 settles down earlier indications of nonnegligible plasma optical thickness in He i D3 expressed in House and Smartt (1982); Athay et al (1983); López Ariste and Casini (2002); Casini et al (2003); and Wiehr and Bianda (2003) in the context of the observed ratios ranging from 6 to 7.6.…”

Section: Introductionsupporting

confidence: 86%

“…This may indicate an inadequacy of the adopted seven-parameter double-Gaussian model. The blue wing excess is also apparent in the He i D3 Stokes I profiles shown in Landman, Edberg, and Laney (1977); House and Smartt (1982); López Ariste and Casini (2002; Casini et al (2003Casini et al ( , 2009and López Ariste and Aulanier (2007). Therefore, in the following we examine alternative He i D3 fitting models with the aim to propose a new model that appears to be characterized by small and featureless differences ∆I and negligible blue wing excess as well.…”

Section: Alternative Fitting Modelsmentioning

confidence: 83%

“…The previous studies by, e.g., Landi Degl'Innocenti (1982); Querfeld et al (1985); López Ariste and Casini (2002; Casini et al (2003Casini et al ( , 2009); Ramelli and Bianda (2005); López Ariste and Aulanier (2007); and Paletou (2008) reported the Stokes Q, U, V amplitudes ranging from 4 × 10 −3 % to 2.3 %. Is the weak polarimetric signal a possible consequence of some inherent feature of this particular target prominence?…”

Section: Small Stokes Q U V Amplitudesmentioning

confidence: 85%

“…In a study of eight prominences, Athay et al (1983) found the He i D3 peak intensity ratios ranging from 6.1 to 7.6. Finally, López Ariste and Casini (2002) and Wiehr and Bianda (2003) reported peak intensity ratios of 6.8 and 6, respectively. While the former two studies employed the double-Gaussian model, the method of inferring the ratios in the latter two articles is unclear.…”

Section: Spectral Characteristics Of the Double-gaussian Modelmentioning

confidence: 98%

See 3 more Smart Citations

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

et al. 2017

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 86%

Section: Alternative Fitting Modelsmentioning

confidence: 83%

Section: Small Stokes Q U V Amplitudesmentioning

confidence: 85%

Section: Spectral Characteristics Of the Double-gaussian Modelmentioning

confidence: 98%

See 2 more Smart Citations

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

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Its main purpose was to provide an alternative way of inverting spectropolarimetric data to determine the vector magnetic field present in various solar features, from sunspots to solar prominences (see e.g., López Ariste & Casini 2002).…”

Section: Introductionmentioning

confidence: 99%

A critical evaluation of the principal component analysis detection of polarized signatures using real stellar data

Paletou

2012

A&A

View full text Add to dashboard Cite

The general context of this study is the post-processing of multiline spectropolarimetric observations of stars, and in particular the numerical analysis techniques aiming at detecting and characterizing polarized signatures. Using real observational data, we compare and clarify several points concerning various methods of analysis. We applied and compared the results of simple line addition, least-squares deconvolution, and denoising by principal component analysis to polarized stellar spectra available from the TBLegacy database of the Narval spectropolarimeter. This comparison of various approaches of distinct sophistication levels allows us to make a safe choice for the next implementation of on-line post-processing of our unique database for the stellar physics community.

show abstract

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Bommier

2016

JGR Space Physics

View full text Add to dashboard Cite

This paper is first devoted to present our method for modeling unresolved magnetic structures in the Milne‐Eddington inversion of spectropolarimetric data. The related definitions and other approaches and different used inversion algorithms are recalled for comparison. In a second part, we apply our method to quiet Sun data outside active regions. We obtain the quiet Sun photospheric magnetic field as composed of unresolved opening and connected magnetic flux tubes, which form a loop carpet of field lines. We then analyze the spatial correlation, which we also observed for the magnetic field vector, in terms of flux tube diameter, distance, and field strength. We find that different observations with the Zurich imaging polarimeter and THEMIS polarimeter mounted on the THEMIS telescope give very close results, and we add results also very close derived from HINODE/Solar Optical Telescope/spectropolarimeter observations analyzed with the same method. We obtain a mean flux tube diameter of 30 km, a mean flux tube distance of 230 km, and a mean flux tube magnetic field of 1.3 kG.

show abstract

Magnetic Fields in Prominences: Inversion Techniques for Spectropolarimetric Data of the HeiD₃Line

Cited by 80 publications

References 18 publications

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

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

A critical evaluation of the principal component analysis detection of polarized signatures using real stellar data

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Contact Info

Product

Resources

About

Magnetic Fields in Prominences: Inversion Techniques for Spectropolarimetric Data of the HeiD3Line

Cited by 80 publications

References 18 publications

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

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

A critical evaluation of the principal component analysis detection of polarized signatures using real stellar data

Milne‐Eddington inversion for unresolved magnetic structures in the quiet Sun photosphere

Contact Info

Product

Resources

About

Magnetic Fields in Prominences: Inversion Techniques for Spectropolarimetric Data of the HeiD₃Line