Multi-Wavelength Eclipse Observations of a Quiescent Prominence

Jejčič, S.; Heinzel, P.; Zapiór, Maciej; Druckmüller, Miloslav; Gunár, S.; Kotrč, P.

doi:10.1007/s11207-014-0482-1

Cited by 11 publications

(6 citation statements)

References 18 publications

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“…To demonstrate the importance of photoionization, we can use [16] as an example. These authors analysed prominence observations which exhibit a systematic increase of the electron density towards the lower parts of the observed prominence.…”

Section: (C) Ionization Structure In a Two-dimensional Filament Modelmentioning

confidence: 99%

“…These authors analysed prominence observations which exhibit a systematic increase of the electron density towards the lower parts of the observed prominence. As [16] showed, the trend when the bottom parts of prominences have higher electron densities can be explained by more efficient photoionization by the Lyman-continuum in the plasma closer to the solar surface. The higher photoionization efficiency near the illuminated surface is caused by the fact that the Lyman continuum is optically thick at its edge at 912 Å in the cool prominence plasma (e.g.…”

Section: Hydrogen Ionizationmentioning

confidence: 99%

“…To analyse these photoionization efficiencies, [16] used a two-dimensional horizontally infinite filament model. The model is isothermal and isobaric, with a temperature of 8000 K and pressure of 0.05 dyn normalcm−2, it has a square cross section with dimensions of 10 000 km and the altitude above the solar surface was set to 40 000 km.…”

Section: Hydrogen Ionizationmentioning

confidence: 99%

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Partial ionization of plasma in solar prominences

Heinzel,

Gunár,

Jejčič

2024

Phil. Trans. R. Soc. A.

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The plasma in cool cores of solar prominences is partially ionized and its ionization degree, in general, depends on the actual kinetic temperature and density of the plasma and the ions considered. However, we demonstrate that under typical prominence conditions, the dominant mechanism contributing to partial ionization is photoionization by radiation diffusing through the plasma. This mechanism strongly depends on the radiation illuminating prominences from the surrounding solar atmosphere. The understanding of the partial ionization of prominence plasma thus requires a complex solution of the non-LTE radiative-transfer problem. In this paper, we discuss the ionization of hydrogen, helium and some other important species. We also demonstrate the role of non-equilibrium ionization. This article is part of the theme issue ‘Partially ionized plasma of the solar atmosphere: recent advances and future pathways’.

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Section: (C) Ionization Structure In a Two-dimensional Filament Modelmentioning

confidence: 99%

Section: Hydrogen Ionizationmentioning

confidence: 99%

Section: Hydrogen Ionizationmentioning

confidence: 99%

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Partial ionization of plasma in solar prominences

Heinzel,

Gunár,

Jejčič

2024

Phil. Trans. R. Soc. A.

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“…The Heinzel et al (2015) model provides a 1D prominence slab with ionization in the center of it, which is a good representation of the ionization degree, although some differences will occur at surface layers. Furthermore, variations in the electron density, for example in 2D models, have also been reported (Jejčič et al 2014). Therefore, different non-LTE models would probably provide different results for the first adiabatic exponent as well as for the slow waves period.…”

Section: The First Adiabatic Exponent γ 1 In the Non-lte Casementioning

confidence: 99%

The first adiabatic exponent in a partially ionized prominence plasma: Effect on the period of slow waves

Ballester

Soler

Carbonell

et al. 2021

A&A

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Partially ionized plasmas are found in many different astrophysical environments. The study of partially ionized plasmas is of great interest for solar physics because some layers of the solar atmosphere (photosphere and chromosphere) as well as solar structures, such as spicules and prominences, are made of these kinds of plasmas. To our knowledge, despite it being known that the adiabatic coefficient, γ, or the first adiabatic exponent, Γ1, depend on the ionization degree, this fact has been disregarded in all the studies related to magnetohydrodynamic waves in solar partially ionized plasmas. However, in other astrophysical areas, the dependence of γ or Γ1 on the plasma ionization degree has been taken into account. Therefore, our aim here is to study how, in a plasma with prominence physical properties, the joint action of the temperature, density, and ionization degree modifies the numerical values of the first adiabatic exponent Γ1 which affects the adiabatic sound speed and the period of slow waves. In our computations, we have used two different approaches; first of all, we assume local thermodynamic equilibrium (LTE) and, later, we consider a non-local thermodynamic equilibrium (non-LTE) model. When comparing the results in the LTE and non-LTE cases, the numerical values of Γ1 are clearly different for both and they are probably strongly dependent on the assumed model which determines how the ionization degree evolves with temperature. Finally, the effect of the ionization degree dependence of Γ1 on the period of slow waves has been determined showing that it can be of great importance for seismological studies of partially ionized solar structures.

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“…Although these works are mostly addressed to amateur astronomers, teachers and educators, they also showed that, even though not explicitly designed for scientific applications, DSLR cameras can nevertheless produce high-quality data only a minimal investment of funds. Surprisingly, the above list of published papers shows a very limited number of works doing research with DSLR cameras in solar physics, with the exception of a few recent works focusing on the measurement of plasma physical parameters in a quiescent prominence (Jejčič et al 2014) based on the method by Jejčič & Heinzel (2009), the determination of contact times of solar eclipses and planetary transits across the solar disk (Di Giovanni 2016), the measurement of the apparent variations of the size of the Sun (Trillenberg 2019), and the recent observations of the total solar eclipse (TSE) of 21st August 2017 (Pasachoff et al 2018;Snik et al 2020). In particular, the latter spectacular event was observed by thousands of people as the path of totality crossed the whole US country from coast to coasts, and allowed for the first time to involve the general public on vast citizen science projects, for instance to observe cloud and temperature properties associated with the transit of the eclipse (Dodson et al 2019), to measure the ionospheric response to the variable solar illumination (Frissell et al 2018), to capture (with the "Citizen CATE Experiment"; Penn et al 2020) a time sequence of white-light coronal observations with identical instruments over ∼ 90 minutes of totality, or to collect (with the "Eclipse Megamovie Project"; Hudson et al 2011) all DSLR pictures of the solar eclipse acquired by people across the US to create a movie showing the high-resolution coronal dynamics close to the limb (see Hudson et al 2018;Peticolas et al 2019, for first results).…”

Section: Introductionmentioning

confidence: 99%

Coronal Electron Densities derived with Images acquired during the 21 August 2017 Total Solar Eclipse

Bemporad

2020

Preprint

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The total solar eclipse of August 21st, 2017 was observed with a Digital Single Lens Reflex (DSLR) camera equipped with a linear polarizing filter. A method was developed to combine images acquired with 15 different exposure times (from 1/4000 sec to 4 sec), identifying in each pixel the best interval of detector linearity. The resulting mosaic image of the solar corona extends up to more than 5 solar radii, with a projected pixel size by 3.7 arcsec/pixel, and an effective image resolution by 10.2 arcsecs, as determined with visible α−Leo and ν−Leo stars. Image analysis shows that in the inner corona the intensity gradients are so steep, that nearby pixels shows a relative intensity difference by up to ∼ 10%; this implies that careful must be taken when analyzing single exposures acquired with polarization cameras.Images acquired with two different orientations of the polarizer have been analyzed to derive the degree of linear polarization, and the polarized brightness pB in the solar corona. After inter-calibration with pB measurements by the K-Cor instrument on Mauna Loa Solar Observatory (MLSO), data analysis provided the 2D coronal electron density distribution from 1.1 up to ∼ 3 solar radii. The absolute radiometric calibration was also performed, with the full sun image, and with magnitudes of visible stars. The resulting absolute calibrations show a disagreement by a factor ∼ 2 with respect to MLSO; interestingly, this is the same disagreement recently found with eclipse predictions provided by MHD numerical simulations.

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Multi-Wavelength Eclipse Observations of a Quiescent Prominence

Cited by 11 publications

References 18 publications

Partial ionization of plasma in solar prominences

Partial ionization of plasma in solar prominences

The first adiabatic exponent in a partially ionized prominence plasma: Effect on the period of slow waves

Coronal Electron Densities derived with Images acquired during the 21 August 2017 Total Solar Eclipse

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