scholarly journals Experiment to Determine the Temperature Structure in the Solar Chromosphere and Corona

1972 ◽  
Vol 14 ◽  
pp. 668-669
Author(s):  
C. R. Negus
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Research Unit ◽  
Emission Lines ◽  
Solar Chromosphere ◽  
Temperature Structure ◽  
Ultraviolet Emission ◽  
Ionization Temperature ◽  
Intensity Ratios

An experiment is in course of preparation at the Astrophysics Research Unit at Culham for flight on a Sun-pointing rocket. It is designed to determine the ionization temperature and electron density as a function of height in the temperature range of about 8 × 104 K to 3 × 106 K by measuring limb to disk intensity ratios of extreme ultraviolet emission lines in the 170 to 850 Å region. The work is an extension of current experiments in which normal-incidence spectrographs are used to determine the structure lower in the chromosphere-corona transition region.

scholarly journals The extreme Ultraviolet emission from the Sun between the Lyman-alpha lines of H I and C VI

1965 ◽  
Vol 23 ◽  
pp. 5-23 ◽  
Author(s):  
R. Tousey ◽  
W. E. Austin ◽  
J. D. Purcell ◽  
K. G. Widing
Keyword(s):  
Extreme Ultraviolet ◽  
Active Regions ◽  
Normal Incidence ◽  
Ultraviolet Spectrum ◽  
Emission Lines ◽  
Continuum Emission ◽  
The Sun ◽  
Ultraviolet Emission ◽  
Lyman Alpha ◽  
Intense Emission

As a result of research carried out with rocket-borne grating spectrographs, the nature of the extreme ultraviolet spectrum of the Sun is now known to a short wavelength limit of 33.7 Å, the Lyman-alpha line of C VI. Most of the emission lines of wavelengths greater than 400 Å have been identified, as have those from 80 Å to 33.7 Å. Between 149 Å and 400 Å, however there are many intense emission lines whose identity has not as yet been established. Twenty or more have been proved to be from iron, since they appear in spectra obtained from high temperature plasmas into which iron has been introduced, but the stages of ionization have not yet been established. Lines from the elements most abundant in the Sun, H, He, O, N, O, Ne, Mg, Al, Si, S and Fe, in most of the stages of ionization requiring 500 eV or less for production have been found. The outstanding exceptions are the lines in the fluorine and neon sequences.Spectroheliograms, photographed with normal incidence spectrographs, show that the emission lines Fe XV 284 Å, Fe XVI 335, 361 Å, originate principally from active regions, in contrast to He II 304 Å, which is emitted with great intensity from the disc also. Continuum emission, in the wavelength range 170–300 Å, has been recorded from intense centers of activity.

scholarly journals Extreme Ultraviolet Spectroscopy of Magnetic Cataclysmic Variables

1996 ◽  
Vol 152 ◽  
pp. 309-316
Author(s):  
Frits Paerels ◽  
Min Young Hur ◽  
Christopher W. Mauche
Keyword(s):  
High Resolution ◽  
White Dwarf ◽  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Ultraviolet Spectroscopy ◽  
Temperature Structure ◽  
Polar Cap ◽  
Ultraviolet Emission ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

A longstanding problem in the interpretation of the X-ray and extreme ultraviolet emission from strongly magnetic cataclysmic variables can be addressed definitively with high resolution EUV spectroscopy. A detailed photospheric spectrum of the accretion-heated polar cap of the white dwarf is sensitive in principle to the temperature structure of the atmosphere. This may allow us to determine where and how the bulk of the accretion energy is thermalized. The EUVE data on AM Herculis and EF Eridani are presented and discussed in this context.

Extreme‐Ultraviolet Emission Lines of Sxin Solar Flare and Active Region Spectra

2004 ◽  
Vol 601 (1) ◽  
pp. 565-569 ◽  
Author(s):  
F. P. Keenan ◽  
A. C. Katsiyannis ◽  
K. G. Widing
Keyword(s):  
Active Region ◽  
Solar Flare ◽  
Extreme Ultraviolet ◽  
Emission Lines ◽  
Ultraviolet Emission

scholarly journals Extreme ultraviolet emission lines of Ar XIV in solar active region and flare spectra

2003 ◽  
Vol 346 (1) ◽  
pp. 58-62 ◽  
Author(s):  
F. P. Keenan ◽  
A. C. Katsiyannis ◽  
R. H. G. Reid ◽  
A. K. Pradhan ◽  
H. L. Zhang ◽  
...  
Keyword(s):  
Active Region ◽  
Extreme Ultraviolet ◽  
Solar Active Region ◽  
Emission Lines ◽  
Ultraviolet Emission

Extreme‐Ultraviolet Emission Lines of Sxiiin Solar Active Region and Flare Spectra

2002 ◽  
Vol 566 (1) ◽  
pp. 521-527 ◽  
Author(s):  
F. P. Keenan ◽  
A. C. Katsiyannis ◽  
R. S. I. Ryans ◽  
R. H. G. Reid ◽  
H. L. Zhang ◽  
...  
Keyword(s):  
Active Region ◽  
Extreme Ultraviolet ◽  
Solar Active Region ◽  
Emission Lines ◽  
Ultraviolet Emission

scholarly journals Further Observations of the Structure of the Chromosphere-Corona Transition Region from Limb and Disk Intensities

1974 ◽  
Vol 56 ◽  
pp. 89-90
Author(s):  
W. M. Burton ◽  
C. Jordan ◽  
A. Ridgeley ◽  
R. Wilson
Keyword(s):  
Transition Region ◽  
Solar Spectrum ◽  
Independent Method ◽  
Emission Lines ◽  
Arc Length ◽  
Rocket Flight ◽  
Steep Rise ◽  
Length Measurements ◽  
Absolute Height ◽  
Intensity Ratios

Further observations of limb and disk intensity ratios of emission lines in the EUV solar spectrum were obtained on a Skylark rocket flight on 5 August 1971. Analysis of the data has shown that the observations support the existence of a steep rise in temperature in the transition region between Te ~ 6 × 104 K and 3 × 105 K. The average absolute height of the transition region above the visible limb has been measured with a greater accuracy than previously possible and is 1700 km ± 700 km. An independent method using arc-length measurements of spectrum lines gives an absolute height of 2100 km ± 850 km. Emission from lines which are optically thick in spicules is observed to extend to heights of 10000 km above the transition region. The observed decrease of Fen emission with height is consistent with current spicule statistics.

Extreme Ultraviolet Emission Lines of Fe XIII in Solar and Stellar Spectra

1995 ◽  
Vol 453 ◽  
pp. 906 ◽  
Author(s):  
F. P. Keenan ◽  
V. J. Foster ◽  
J. J. Drake ◽  
S. S. Tayal ◽  
K. G. Widing
Keyword(s):  
Extreme Ultraviolet ◽  
Emission Lines ◽  
Ultraviolet Emission ◽  
Stellar Spectra
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