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Mein, P.; Mein, N.; Malherbe, Jean-Marie; Heinzel, P.; Kneer, F.; Uexküll, M. von; Staiger, J.

doi:10.1023/a:1004993012259

Cited by 38 publications

(49 citation statements)

References 2 publications

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“…A thorough description of the code and its boundary conditions is given in N. , Heinzel et al (1999) and Molowny-Horas et al (1999), the application to Ca ii is worked out in Mein et al (2000).…”

Section: Ca II Mali Code Synthetic Profile Calculationsmentioning

confidence: 99%

“…The computed depth-dependent mean resonance line and continuum intensities are used for the evaluation of the Ca ii photoionization rates. The non-LTE MALI computation of the Ca ii follows, according to Mein et al (2000).…”

Section: Ca II Mali Code Synthetic Profile Calculationsmentioning

confidence: 99%

“…Recently Socas-Navarro et al (1998) used the response function concept with the fixed departure coefficient (FDC) approximation for the non-LTE inversion of several chromospheric line profiles including the Ca ii 8542Å line. Mein et al (1987) proposed the decomposition of observed profiles into their Fourier components. Their idea of linking thermodynamical parameters of theoretical model profiles to the Fourier coefficients and studying the corresponding variations was first applied to observed Send offprint requests to: K. Tziotziou, e-mail: Kostas.Tziotziou@obspm.fr…”

Section: Introductionmentioning

confidence: 99%

“…In cloud models the emerging chromospheric line profiles consist of the background line profiles, partially absorbed by the cloud, and the radiation emitted by the cloud itself. Although the simple cloud model proposed by Beckers (1964) has been criticized for failing to explain Hα contrast profiles of chromospheric fine structures (Cram 1975), improved cloud models have been successful for the study of several chromospheric features like filaments (Molowny-Horas et al 1999), arch filaments (P. Mein et al 2000) and mottles (Tsiropoula et al 1993).…”

Section: Introductionmentioning

confidence: 99%

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Non-LTE inversion of chromospheric Caii cloud-like features

Tziotziou

Heinzel

Mein

et al. 2001

A&A

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Abstract.A chromospheric cloud-like feature observed in the 8542Å Ca ii line is studied by a two step inversion procedure which provides estimates of its temperature, electronic density, microturbulence, geometrical thickness and bulk velocity. The first step involves the computation of a large grid of models by a multi-level non-LTE transfer code which gives the Ca ii line depth-dependent mean intensity inside an isolated, isothermal cloud lying above the chromosphere. The second step involves the inversion of the observed profiles with the grid of computed synthetic Ca ii profiles. A searching and matching χ 2 algorithm is implemented followed by an interpolation algorithm which permits a more accurate determination of the parameters on which the profiles depend. The five grid parameters are reduced to four by defining the emission measure from the geometrical thickness and electronic density. We show that this inversion procedure gives accurate results for some of our inversion parameters when dealing with solar filaments and is complementary to a previous study of the same object in the Hα line. The main advantages, problems and future extension of the inversion approach are also discussed.

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Section: Ca II Mali Code Synthetic Profile Calculationsmentioning

confidence: 99%

Section: Ca II Mali Code Synthetic Profile Calculationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-LTE inversion of chromospheric Caii cloud-like features

Tziotziou

Heinzel

Mein

et al. 2001

A&A

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“…and mode 2 for H α . Thanks to the good seeing of Tenerife, many topics were investigated, either with H α alone, such as the dynamics of arch filament systems (Mein et al 1996) and the non-LTE inversion of prominence profiles (Molowny-Horas et al 1999), or with H α and 854.2 CaII, such as asymmetries of flare profiles (Mein et al 1997) and Fourier analysis of sunspot oscillations (Tziotziou et al 2007).…”

Section: Specific Capabilitiesmentioning

confidence: 99%

Fast imaging spectroscopy with MSDP spectrometers. Vector magnetic maps with THEMIS/MSDP

Mein¹,

Mein²,

Bommier

2009

A&A

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Context. Multichannel subtractive double pass (MSDP) spectrometers produce 3D data cubes (x, y, λ) simultaneously across several line profiles. They do not suffer from image convolution by any slit width, and synchronous observations across all wavelengths avoid differential seeing effects. They are very suitable for fast 2D spectroscopy. Aims.(1) We review specifications and capabilities of some existing MSDP spectrometers with respect to high-cadence observations. (2) THEMIS/MSDP is designed for the spectropolarimetry of strong lines. We propose new data reductions also suitable for the spectropolarimetry of photospheric lines.Methods. An off-line algorithm is described as a way to increase the spectral resolution. Taking the opportunity of 3D data, spatial interpolations are used around each solar point by only assuming that intensity gradients ∂I(x, y, λ)/∂x are constant in the range (x ± x , λ ± λ ). The UNNOFIT inversion is used to compare vector magnetic maps deduced from THEMIS/MSDP and slitspectropolarimetry THEMIS/MTR data. Results. Both results are in good agreement. In active regions, the rms of the MSDP noise, calculated over 1 arcsec 2 , is less than 24 G for the LOS magnetic field and less than 52 G for B x and 32 G for B y . The MSDP scanning speed is 10 times the speed of slit-spectropolarimetry. Conclusions. THEMIS/MSDP can provide vector magnetic maps with typical temporal resolutions that are less than 1 min for small fields-of-view and 10 min for active regions. This allows addressing a number of fast events. In the future, MSDP instruments should efficiently complement single-slit spectroscopy and tunable filters. Their main capabilities should be the multiline aspect and the high temporal and spatial resolutions. New optical devices, such as image slicers, should substantially increase the signal-to-noise ratio. For polarimetric measurements, various compromises are possible between speed, spatial resolution, and SNR. A-posteriori image restorations, either using wide band proxies or bursts of multi-wavelength short exposures, should help improving signal-to-noise ratio and spatial resolution.

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Derivations and Observations of Prominence Bulk Motions and Mass

Kucera¹

2014

Solar Prominences

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In this chapter we review observations and techniques for measuring both bulk flows in prominences and prominence mass. Measuring these quantities is essential to development and testing of models discussed throughout this book. Prominence flows are complex and various, ranging from the relatively linear flows along prominence spines to the complex, turbulent patterns exhibited by hedgerow prominences. Techniques for measuring flows include time slice and optical flow techniques used for motions in the plane of the sky and the use of spectral line profiles to determine Doppler velocities along the line of sight. Prominence mass measurement is chiefly done via continuum absorption measurements, but mass has also been estimated using cloud modeling and white light measurements.Comment: in Solar Prominences, eds. J.-C. Vial and O. Engvold, Springer, p. 79, 201

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Untitled

Cited by 38 publications

References 2 publications

Non-LTE inversion of chromospheric Caii cloud-like features

Non-LTE inversion of chromospheric Caii cloud-like features

Fast imaging spectroscopy with MSDP spectrometers. Vector magnetic maps with THEMIS/MSDP

Derivations and Observations of Prominence Bulk Motions and Mass

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