Observations of neutral hydrogen in the corona

Kim, I. S.; Попов, В. В.; Lisin, D. V.; Osokin, A.P.

doi:10.1134/s0016793213070104

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…This resulted in factual angular resolution of 8′′ or 12′′ in polarization images. Details of observations, data reduction, and 2‐D distributions of p ( p ‐images) were discussed recently [ Kim et al ., , ].…”

Section: Total Solar Eclipse As An Approachmentioning

confidence: 99%

Imaging the structure of the low K‐corona

et al. 2017

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The first 2‐D distributions of the polarization angle and of the relative color index for the K‐corona of 29 March 2006 are presented. The distributions illustrate the efficiency of the total solar eclipse approach for high‐precision measurements of the K‐corona continuum in the range < 1.4 R⊙. Natural ground and space total solar eclipses caused by external occulting the bright solar‐disk light by the Moon or Earth group planets are discussed. Calculations of the eclipse magnitude m are carried out to show ideal conditions for total solar eclipse observations in space from Lagrange point L2 for Mars (m ≈ 1.025). The illumination in Mars' shadow is estimated to equal 5.6 × 10−11 for the wavelength of 550 nm. No internal or external occulting coronagraphs are needed. Partial solar eclipses with m > 0.91 can be observed from Lagrange points L2 for Mercury, Venus, and Earth.

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Section: Total Solar Eclipse As An Approachmentioning

confidence: 99%

Imaging the structure of the low K‐corona

et al. 2017

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“…Another possibility has been opened with eclipse polarization measurements in red and green channels by Kim et al (2013b) from which these authors concluded that "the polarization excess (green-red) can be explained by the presence of neutral hydrogen in the corona" (see also Dolei et al, 2014). As mentioned by Kim et al (2013b), Poland and Munro (1976) and Mierla et al (2011) had already concluded that Hα contributed to coronagraphic images of transients and coronal mass ejections (CMEs), respectively. Actually this was demonstrated with eclipse measurements made at the Canada-France-Hawaï Telescope (CFHT) in 1991 where Vial et al (1992) detected a plasmoid in the solar corona that Koutchmy et al (1994) interpreted as emitting essentially in the Hα line, a claim discussed later on by Zhukov et al (2000) who proposed an upper limit of the emission of about 2 % of the background corona.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from radio observations above active regions, another path towards coronal polarimetry has been pursued with ground-based infrared (IR) observations measuring the Zeeman effect (Lin, Penn, and Tomczyk, 2000;Tomczyk et al, 2008). Another possibility has been opened with eclipse polarization measurements in red and green channels by Kim et al (2013b) from which these authors concluded that "the polarization excess (green-red) can be explained by the presence of neutral hydrogen in the corona" (see also Dolei et al, 2014). As mentioned by Kim et al (2013b), Poland and Munro (1976) and Mierla et al (2011) had already concluded that Hα contributed to coronagraphic images of transients and coronal mass ejections (CMEs), respectively.…”

Section: Introductionmentioning

confidence: 99%

Neutral Hydrogen and Its Emission Lines in the Solar Corona

Vial

Chane-Yook

2016

Sol Phys

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Since the Lα rocket observations of (Gabriel, Solar Phys. 21, 392, 1971), it has been realized that the hydrogen (H) lines could be observed in the corona and offer an interesting diagnostic for the temperature, density, and radial velocity of the coronal plasma. Moreover, various space missions have been proposed to measure the coronal magnetic and velocity fields through polarimetry in H lines. A necessary condition for such measurements is to benefit from a sufficient signal-to-noise ratio. The aim of this article is to evaluate the emission in three representative lines of H for three different coronal structures. The computations have been performed with a full non-local thermodynamicequilibrium (non-LTE) code and its simplified version without radiative transfer. Since all collisionnal and radiative quantities (including incident ionizing and exciting radiation) are taken into account, the ionization is treated exactly. Profiles are presented at two heights (1.05 and 1.9 solar radii, from Sun center) in the corona, and the integrated intensities are computed at heights up to five solar radii. We compare our results with previous computations and observations (e.g. Lα from UVCS) and find a rough (model-dependent) agreement. Since the Hα line is a possible candidate for ground-based polarimetry, we show that in order to detect its emission in various coronal structures, it is necessary to use a very narrow (less than 2Å wide) bandpass filter.

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Heliophysics at total solar eclipses

Pasachoff

2017

Nat Astron

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Observations of neutral hydrogen in the corona

Cited by 4 publications

References 7 publications

Imaging the structure of the low K‐corona

Imaging the structure of the low K‐corona

Neutral Hydrogen and Its Emission Lines in the Solar Corona

Heliophysics at total solar eclipses

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