Non-LTE Inversion of Prominence Spectroscopic Observations in Hα and Mg ii h&amp;k lines

Jejčič, S.; Heinzel, P.; Schmieder, B.; Gunár, S.; Mein, P.; Mein, N.; Ruan, Guiping

doi:10.3847/1538-4357/ac6bf5

Cited by 8 publications

(1 citation statement)

References 38 publications

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“…Nevertheless, there have been significant advances in fundamental chromospheric science enabled by state-of-the-art inversions applied to high-resolution observations, for example in evaluating the role of magnetic fields in the heating of the quiet Sun chromosphere through ubiquitous magnetic flux cancellation events (Gošić et al, 2018), in inferring the stratification of the atmosphere undergoing magnetic reconnection (Vissers et al, 2019;Díaz Baso et al, 2021), in constraining heating rates due to emerging magnetic flux in an active region (da Silva Santos et al, 2022), in assessing the role of Alfvén waves and ion-neutral effects in plage heating (Anan et al, 2021), and in constraining temperatures of off-limb solar structures such as prominences (Jejčič et al, 2022) and spicules (Kuridze et al, 2021).…”

Section: Current Situationmentioning

confidence: 99%

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Reardon,

Milic,

Santos

et al. 2023

Bulletin of the AAS

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Advances in our understanding of the Sun will require the accurate and consistent measurement of the physical conditions in different regions of the solar atmosphere. The richest information, encoding the full state integrated over of the atmospheric volume in which they are formed, is contained in the detailed shapes of the numerous spectral lines present in the solar spectrum. But this integration along the line of sight is highly non-linear, which means that inferring the true physical conditions requires solving a complicated, ill-posed inverse problem. This challenge is being addressed through powerful codes that treat ever more complex aspects of the solar atmosphere -the breakdown of local thermodynamic equilibrium (or non-LTE), non-equilibrium hydrogen ionization, deviations from hydrostatic equilibrium, and multiple methods of deriving chromospheric and coronal magnetic fields. However, to reach the full potential of these techniques, the community must make a concerted, sizable effort to improve and enhance them, both in terms of their physical veracity as well as their computational tractability. These methods will be essential for fully exploiting the data from new and proposed solar facilities or missions. Reliable outputs from inversions will be a key component of more realistic extrapolations of the magnetic field of active regions and the heliosphere. These inversion methods, if accurate and robust, can become a key tool in determining the structure of stellar atmospheres, but will also become crucial for the operational prediction of the energetics of the Sun's magnetic field and the driving of space weather and changes in the solar spectral irradiance.

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Section: Current Situationmentioning

confidence: 99%

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Reardon,

Milic,

Santos

et al. 2023

Bulletin of the AAS

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Two-horn quiescent prominence observed in Hα and Mg II h&k lines with THEMIS and IRIS

Barczynski,

Schmieder,

Gelly

et al. 2023

A&A

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Context. Prominences are large magnetic structures in the corona filled by cool plasma with fast evolving fine structure. Aims. We aim to better understand the plasma conditions in the fine structure of a quiescent prominence including two transient horns observed at the bottom of the cavity using the high resolution Interface Region Imaging Spectrograph (IRIS) and the MulTi-Raies (MTR) spectrograph of the Télescope Heliographique pour l’Etude du Magnétisme et des Instabilités Solaires (THEMIS) in the Canary Islands. Methods. We analysed the spectra obtained in Hα by THEMIS and Mg II by IRIS and compare them with a grid of 23 940 1D radiative transfer models which include a prominence-to-corona transition region (PCTR). The full observed profiles of Mg II in each pixel are fitted completely by synthesised profiles with ×RMS (Cross RMS; an improved version of the rolling root mean square (rRMS) method). When the RMS is below a certain threshold value, we recover the plasma conditions from the parameters of the model best fitting the observed line profile. This criterion is met in two regions (the horns and edge of the prominence) where the line profiles can generally be described as single peaked. Results. The 1D models suggest that two different kinds of model atmospheres correspond to these two regions. The region at the edge is found to be fitted mainly with isothermal and isobaric models, while the other area (the horns) is seen to be fitted with models with a PCTR that have optical thicknesses of less than 5. In the prominence edge, the theoretical relationship between the integrated intensities in Hα and Mg II is verified and corresponds to low emission measure values. In these regions the electron density is around 1010 cm−3, while it is one order of magnitude less in the horn regions around 109 cm−3. Conclusions. In the horns, we find some profiles are best fitted with models with high mean temperatures. This suggests that the hot PCTR found in the horns could be interpreted as prominence plasma in condensation phase at the bottom of the coronal cavity.

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The diversity of spectral shapes of hydrogen Lyman lines and Mg II lines in a quiescent prominence

Schwartz,

Gunár,

Koza

et al. 2024

A&A

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Broad sets of spectroscopic observations comprising multiple lines represent an excellent opportunity for diagnostics of the properties of the prominence plasma and the dynamics of their fine structures. However, they also bring significant challenges when they are compared with synthetic spectra provided by radiative transfer modeling. In this work, we provide a statistical spectroscopic analysis of a unique dataset of coordinated prominence observations in the Lyman lines (Lyalpha to Lydelta ) and the Mg ii k and h lines. The observed data were obtained by the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrograph on board of the Solar and Heliospheric Observatory (SoHO) satellite and the Interface Region Imaging Spectrograph (IRIS) on 22 October 2013. Only a few similar coordinated datasets of Lyman and Mg ii k and h observations have ever been obtained in prominences and we present here the first analysis using these two sets of spectral lines. Moreover, for the first time, we assess the influence of noise on the statistical properties of the studied profile characteristics. We focus on the following profile characteristics: the shape of the observed line profiles based on the number of distinct peaks, the integrated line intensity, the center-to-peak ratio describing the depth of the reversal of two-peaked profiles, and the asymmetry of these peaks. We show that the presence of noise has a negligible effect on the integrated intensity of all observed lines, but it significantly affects the classification of spectral profiles using the number of distinct peaks, the reversal depth, and also the peak asymmetry. We also demonstrate that by taking the influence of noise into account, we can assess which profile characteristics in which spectral lines are suitable for diagnostics of different properties of the observed prominence. For example, we show that the subordinate peaks (peaks below error bars) in the Lyman line profiles are mostly caused by noise, which means that only the dominant peaks should be used for statistical analyses or comparisons with synthetic spectra. On the other hand, in the Mg ii k and h profiles, the key role in the distinction between the multi peaked profiles with low peaks and the profiles with deep reversals is played by the dynamics of multiple fine structures located along a line of sight. The complex, multi peaked profiles are observed in places where multiple fine structures with different line-of-sight velocities are crossing the line of sight, while the profiles with deep reversals likely correspond to instances when we observe single fine structures or more fine structures but with similar line-of-sight velocities. This study allows us to conclude that if we are interested in the diagnostics of the dynamics of prominence fine structures, the best approach is to use a combination of profile asymmetry in the Lyman lines together with the complex profiles of Mg ii k and h lines. On the other hand, if we want to diagnose the temperature and pressure properties of individual prominence fine structures, we need to focus on the deeply reversed Mg ii k and h lines in combination with the Lyman lines and to analyze the depth of the central reversal and the integrated intensities.

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Non-LTE Inversion of Prominence Spectroscopic Observations in Hα and Mg ii h&k lines

Cited by 8 publications

References 38 publications

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Two-horn quiescent prominence observed in Hα and Mg II h&k lines with THEMIS and IRIS

The diversity of spectral shapes of hydrogen Lyman lines and Mg II lines in a quiescent prominence

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Non-LTE Inversion of Prominence Spectroscopic Observations in Hα and Mg ii h&k lines

Cited by 8 publications

References 38 publications

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Spectropolarimetric inversions: Our key to unlocking the secrets of the solar atmosphere

Two-horn quiescent prominence observed in Hα and Mg II h&k lines with THEMIS and IRIS

The diversity of spectral shapes of hydrogen Lyman lines and Mg II lines in a quiescent prominence

Contact Info

Product

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Two-horn quiescent prominence observed in Hα and Mg II h&k lines with THEMIS and IRIS

The diversity of spectral shapes of hydrogen Lyman lines and Mg II lines in a quiescent prominence