Non‐LTE Radiative Transfer in Model Prominences. I. Integrated Intensities of He<scp>i</scp>Triplet Lines

Labrosse, Nicolas; Gouttebroze, P.

doi:10.1086/425168

Cited by 40 publications

(50 citation statements)

References 24 publications

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“…However, even in these regimes, the optical thicknesses of the D 3 multiplet never exceed τ ∼ 0.1. These results are also in accordance with 1D models of Labrosse & Gouttebroze (2004). For instance, these authors found no model for which the D 3 multiplet is optically thick, and τ(10 830) > 1 for models where T > 20 000 K and p g > 0.64 dyn cm −2 , i.e., conditions that are not representative of those expected in quiescent prominences.…”

Section: Single Slab Modelssupporting

confidence: 78%

“…Then, in Sect. 3 we compare and validate our results against previous works of Labrosse & Gouttebroze (2001& Gouttebroze ( , 2004. We also show how geometrical effects can influence line profiles.…”

Section: Introductionsupporting

confidence: 68%

“…Of particular interest are the recent onedimensional (1D) static slab models of Labrosse & Gouttebroze (2001, 2004, which produce unrealistic Gaussian profiles because they neglect the fine-structure of the helium multiplets.…”

Section: Introductionmentioning

confidence: 99%

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2D non-LTE radiative modelling of He I spectral lines formed in solar prominences

Léger

Paletou

2009

A&A

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Context. The interpretation of high-resolution spectropolarimetric observations of solar prominences completed primarily at visible and near-infrared wavelengths, requires radiative modelling that takes into account both multi-dimensional geometry and complex atomic models.Aims. We enhance the interpretation of observations of He i multiplets, by considering 2D non-LTE unpolarized radiation transfer, and taking into account of the atomic fine-structure of helium. Methods. We apply our 2D non-LTE radiative transfer code, which is based on the multi-grid Gauss-Seidel/SOR iterative schemes.Results. It allows us to compute realistic emergent intensity profiles for the He i λ10 830 Å and D 3 multiplets, which can be directly compared to the simultaneous and high-resolution observations completed at THéMIS. A preliminary 2D multi-thread modelling is also discussed.

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Section: Single Slab Modelssupporting

confidence: 78%

Section: Introductionsupporting

confidence: 68%

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2D non-LTE radiative modelling of He I spectral lines formed in solar prominences

Léger

Paletou

2009

A&A

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“…The importance of the PCTR in prominence modelling has been discussed by Anzer and Heinzel (1999), and its effect on various spectral lines demonstrated by e.g. Heinzel et al (2001), Labrosse and Gouttebroze (2004), Labrosse et al (2010), Heinzel et al (2015b). However, the nature of the PCTR and its relationship to the prominence and prominence fine-structure is not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Rodger

Labrosse

2017

Sol Phys

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Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 -9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 -3.6 mm (Band 3) and 1.1 -1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

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“…Results from [3,5,6] have shown that in solar quiescent prominences (negligible velocity fields) the scattering of the incident radiation coming from the Sun is dominant in the formation of most lines. The contribution of collisional excitation becomes important at high temperatures and pressures.…”

Section: Resultsmentioning

confidence: 99%

Formation of Helium Lines in Solar Prominences

Labrosse¹,

Gouttebroze²

2009

AIP Conference Proceedings

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Abstract. We summarize the results on the formation of the helium spectrum in solar prominences obtained over recent years. The radiative transfer problem under non-LTE conditions is solved to compute the profiles of the lines of He I and He II. The structure of the prominence-to-corona transition region (PCTR) has a major influence on the resulting spectrum of the resonance lines since they are formed mostly in this part of the prominence. However, subordinate lines are also affected by the structure of the PCTR. We pay particular attention to the formation of the He II 304 Å resonance line which is routinely observed from space, but yet not fully understood. Future steps in the modelling will be addressed.

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Non‐LTE Radiative Transfer in Model Prominences. I. Integrated Intensities of HeiTriplet Lines

Cited by 40 publications

References 24 publications

2D non-LTE radiative modelling of He I spectral lines formed in solar prominences

2D non-LTE radiative modelling of He I spectral lines formed in solar prominences

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Formation of Helium Lines in Solar Prominences

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