Rocket Observations of the Ultraviolet Solar Spectrum during the Total Eclipse of 1970 March 7

Gabriel, A. H.; Garton, W. R. S.; Goldberg, Leo; Jones, T. J.; Jordan, C.; Morgan, F.; Nicholls, R. W.; Parkinson, W.J.; Paxton, H. J. B.; Reeves, E. M.; Shenton, C. B.; Speer, R. J.; Wilson, Richard C.

doi:10.1086/151178

Cited by 95 publications

(25 citation statements)

References 8 publications

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“…Many of the 2s 3 S2p 3 P transitions in Ne 8+ , Na 9+ , Mg 10+ , and Si 12+ have recently been observed in solar flare plasmas, in which also the wavelength of the Na X line at 111.177 nm could be measured for the first time (Curdt et al 2000). The corresponding O VII line had been tentatively identified at 162.4 nm in an early eclipse spectrum by Gabriel et al (1971). This identification was then confirmed using Skylab spectra by Feldman and Doschek (1977c).…”

Section: Flaresmentioning

confidence: 80%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

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Section: Flaresmentioning

confidence: 80%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

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“…The emission of the Lα λ1216 line in the solar corona has been discovered by Gabriel et al (1971). They concluded that in most coronal structures the process responsible for the formation of the Lα line is the photo-excitation by underlying radiation.…”

Section: Expression Of the Stokes Parametersmentioning

confidence: 99%

Hanle signatures of the coronal magnetic field in the linear polarization of the hydrogen Lαline

Derouich

Auchère

Vial

et al. 2010

A&A

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Aims. This paper is dedicated to the assessment of the validity of future coronal spectro-polarimetric observations and to prepare their interpretation in terms of the magnetic field vector. Methods. We assume that the polarization of the hydrogen coronal Lα line is due to anisotropic scattering of an incident chromospheric radiation field. The anisotropy is due to geometrical effects but also to the inhomogeneities of the chromospheric regions which we model by using Carrington maps of the Lα. Because the corona is optically thin, we fully consider the effects of the integration over the line-of-sight (LOS). As a modeling case, we include a dipolar magnetic topology perturbed by a non-dipolar magnetic structure arising from a prominence current sheet in the corona. The spatial variation of the hydrogen density and the temperature is taken into account. We determine the incident radiation field developed on the tensorial basis at each point along the LOS. Then, we calculate the local emissivity vector to obtain integrated Stokes parameters with and without coronal magnetic field. Results. We show that the Hanle effect is an interesting technique for interpreting the scattering polarization of the Lα λ1216 line in order to diagnose the coronal magnetic field. The difference between the calculated polarization and the zero magnetic field polarization gives us an estimation of the needed polarimetric sensitivity in future polarization observations. We also obtain useful indications about the optimal observational strategy. Conclusions. Quantitative interpretation of the Hanle effect on the scattering linear polarization of Lα line can be a crucial source of information about the coronal magnetic field at a height over the limb h < 0.7 R . Therefore, one needs the development of spatial instrumentation to observe this line.

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“…At higher levels, and for bright enough exciting chromospheric radiation, lines form also via resonant scattering of radiation: this is the dominant process for the H  Lyα, while both components need to be considered for the O  lines. The Lyα line is produced by resonance scattering (Gabriel et al 1971) and is therefore subject to Doppler dimming (Hyder & Lites 1970). The two lines of the O  resonance doublet are excited in part by collisions with free electrons, in part by transition region radiation (Kohl & Withbroe 1982), therefore their radiative components can be affected by Doppler dimming.…”

Section: Density Estimatementioning

confidence: 99%

Plasma properties above coronal active regions inferred from SOHO/UVCS and radio spectrograph observations

Mancuso¹,

Raymond²,

Kohl³

et al. 2003

A&A

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Abstract. Information on coronal plasma was inferred from the joint analysis of type  radio bursts and SOHO UltraViolet Coronagraph Spectrometer (UVCS) observations. The data sample comprises 37 metric type  radio bursts observed by groundbased radio spectrographs in 1999, during the rising phase of the solar cycle. The coronal electron densities n e were estimated with the diagnostic provided by UVCS observations of the O  doublet line intensities. Upper limits to the coronal Alfvén speed above active regions were inferred from the derived shock speeds by requiring that the disturbances propagate at least faster than the local characteristic speed. Information on the magnetic field strength B and plasma β in the middle corona were finally extracted from the coronal Alfvén speed upper limits. A major improvement with respect to previous studies that used type  radio bursts to derive plasma properties, is that density profiles of the pre-shock plasma obtained a few hours before the passage of the shock were used instead of general electron density models taken from literature. Our main result is expressed by the inequality B(r) ≤ (0.6 ± 0.3)(r − 1) −1.2 G, that is valid in the range 1.5 ≤ r ≤ 2.3 solar radii, and is consistent with previous estimates of the magnetic field above coronal active regions.

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Rocket Observations of the Ultraviolet Solar Spectrum during the Total Eclipse of 1970 March 7

Cited by 95 publications

References 8 publications

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Hanle signatures of the coronal magnetic field in the linear polarization of the hydrogen Lαline

Plasma properties above coronal active regions inferred from SOHO/UVCS and radio spectrograph observations

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