The SUMER Ly-<i>α</i> line profile in quiescent prominences

Curdt, W.; Teriaca, L.; Schühle, U.

doi:10.1051/0004-6361/200913875

Cited by 9 publications

(7 citation statements)

References 21 publications

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“…Similar surprising results were found when we observed the hydrogen Lyman line series in prominences. Some prominences presented profiles that were not systematically reversed Schmieder et al 2007;Gunár et al 2007;Curdt et al 2010;Schwartz et al 2012). This has been discussed in terms of the orientation of the magnetic structures in prominences and the column mass.…”

Section: Mg II Profilesmentioning

confidence: 97%

Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP

Schmieder

Tian

Kucera³

et al. 2014

A&A

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ContextResults. The magnetic field is found to be globally horizontal with a relatively weak field strength (8-15 Gauss). On the other hand, the Ca II movie reveals turbulent-like motion that is not organized in specific parts of the prominence. We tested the addition of a turbulent magnetic component. This model is compatible with the polarimetric observations at those places where the plasma turbulence peaks. On the other hand, the Mg II line profiles show multiple peaks well separated in wavelength. This is interpreted by the existence of small threads along the line of sight with a large dispersion of discrete values of Doppler shifts, from 5 km s −1 (a quasi-steady component) to 60-80 km s −1 . Each peak corresponds to a Gaussian profile, and not to a reversed profile as was expected by the present non-LTE radiative transfer modeling. This is a very surprising behavior for the Mg II line observed in prominences. Conclusions. Turbulent fields on top of the macroscopic horizontal component of the magnetic field supporting the prominence give rise to the complex dynamics of the plasma. The plasma with the high velocities (70 km s −1 to 100 km s −1 if we take into account the transverse velocities) may correspond to condensation of plasma along more or less horizontal threads of the arch-shape structure visible in 304 Å. The steady flows (5 km s −1 ) would correspond to a more quiescent plasma (cool and prominence-corona transition region) of the prominence packed into dips in horizontal magnetic field lines. The very weak secondary peaks in the Mg II profiles may reflect the turbulent nature of parts of the prominence.

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Section: Mg II Profilesmentioning

confidence: 97%

Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP

Schmieder

Tian

Kucera³

et al. 2014

A&A

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“…Observations have shown that the Lyα line has responses to a great variety of solar activities from the chromosphere to the corona, including filaments/prominences (Curdt et al 2010;Chintzoglou et al 2017;Susino et al 2018), type-II spicules (Chintzoglou et al 2018), oscillations (Van Doorsselaere et al 2011;Milligan et al 2017) and flares (Rubio da Costa et al 2009;Milligan & Chamberlin 2016). In particular, the Lyα line is greatly enhanced during flares, and the bright Lyα emission is co-spatial with the hard X-ray sources (Rubio da Costa et al 2009;Milligan & Chamberlin 2016).…”

Section: Introductionmentioning

confidence: 99%

The Response of the Lyα Line in Different Flare Heating Models

Hong

Liu

Ding

et al. 2019

ApJ

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The solar Lyα line is the strongest line in the ultraviolet waveband, and is greatly enhanced during solar flares. Here we present radiative hydrodynamic simulations of solar flares under different heating models, and calculate the response of this line taking into account non-equilibrium ionization of hydrogen and partial frequency redistribution. We find that in non-thermal heating models, the Lyα line can show a red or blue asymmetry corresponding to the chromospheric evaporation or condensation, respectively. The asymmetry may change from red to blue if the electron beam flux is large enough to produce a significant chromospheric condensation region. In the Lyα intensity lightcurve, there appears a dip when the change of asymmetry occurs. In thermal models, the Lyα line intensity peaks quickly and then falls, and the profile has an overall red asymmetry, which is similar to the profiles from heating by a soft electron beam. The Lyα profile shows a single red peak at the end of thermal heating, and the whole line is formed in a very small height range.

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“…The animation is available in electronic form at http://www.aanda.org at 1083 nm (Lites 1986;Rüedi et al 1995;Socas-Navarro & Elmore 2005;Sánchez-Andrade Nuño et al 2007;Kuckein et al 2009;Felipe et al 2010) by the absorption in the Earth's atmosphere, whereas from space Mg ii h and k, Lα, and other lines in the extreme UV are also accessible (e.g., Kneer et al 1981;Bonnet 1981;Fontenla et al 1988;Curdt et al 2010) 1 . Even though the Ca ii H and K lines provide a tremendous amount of information on all of the lower solar atmosphere, it turned out to be rather difficult to extract this information from observed spectra (Linsky & Avrett 1970).…”

Section: Introductionmentioning

confidence: 99%

The energy of waves in the photosphere and lower chromosphere

Beck

Rezaei

Puschmann

2012

A&A

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Context. The Ca ii H line is one of the strongest lines in the solar spectrum, and it provides continuous information on the solar atmosphere from the photosphere to the lower chromosphere.Aims. We describe an inversion approach that reproduces observed Ca ii H spectra by assuming local thermal equilibrium (LTE). Methods. We developed an inversion strategy based on the SIR code that reproduces Ca ii H spectra in the LTE approximation. The approach uses a two-step procedure with an archive of pre-calculated spectra to fit the line core and a subsequent iterative modification to improve the fit mainly in the line wing. Simultaneous spectra in the 630 nm range can optionally be used to fix the continuum temperature. The method retrieves one-dimensional (1D) temperature stratifications while neglecting lateral radiative transport. Lineof-sight velocities are included post facto with an empirical approach.Results. An archive of about 300 000 pre-calculated spectra is more than sufficient to reproduce the line core of observed Ca ii H spectra both in the quiet Sun and in active regions. The subsequent iterative adjustment of the thermodynamical stratification matches observed and best-fit spectra to a level of about 0.5% of I c in the line wing and about 1% of I c in the line core. Conclusions. The successful application of the LTE inversion strategy suggests that inversion schemes based on pre-calculated spectra allow a reliable and relatively fast retrieval of solar properties from observed chromospheric spectra. The approach can be easily extended to a 1D non-LTE (NLTE) case by a simple exchange of the pre-calculated archive spectra. Using synthetic NLTE spectra from numerical three-dimensional (3D) simulations instead will finally allow one to extend the approach from the static 1D-case to dynamical atmosphere models, including the complete 3D radiative transport.

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The SUMER Ly-α line profile in quiescent prominences

Cited by 9 publications

References 21 publications

Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP

Open questions on prominences from coordinated observations by IRIS, Hinode, SDO/AIA, THEMIS, and the Meudon/MSDP

The Response of the Lyα Line in Different Flare Heating Models

The energy of waves in the photosphere and lower chromosphere

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