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  • 1
    Electronic Resource
    Electronic Resource
    Decrease in the Intensity of Hydrogen Lines in the Solar Chromosphere (1968)
    [s.l.] : Nature Publishing Group
    Nature 219 (1968), S. 599-599 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Rouse's computed maximum level n*, where n*2 = 0.59r0/a0, 47cr08/3 = JVY1, and Nt is the number density of atoms and ions, is 31 for a density which he has assigned to a height of about 600 km in the chromosphere. Two recent models5,6 with considerably different temperatures but with ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/219599a0
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  • 2
    Electronic Resource
    Electronic Resource
    Solar rotation in the chromosphere and corona (1973)
    Springer
    Solar physics 33 (1973), S. 425-429 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Extreme ultraviolet spectroheliograms in Mg x (625 Å) and the Lyman continuum (897 Å) obtained from OSO-6 are used to determine the differential rotation rate in the solar chromosphere and corona. The equatorial rotation rate agrees with spectroscopic measurements of the photospheric plasma velocity; the variation of rate with latitude is less pronounced than in most other determinations. We cannot discern a variation in the rotation rate between the chromosphere and corona.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152429
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of the chromospheric hydrogen spectrum at the 1962 eclipse (1969)
    Springer
    Solar physics 9 (1969), S. 65-76 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Slitless spectrograms of the chromosphere obtained during the eclipse of 4–5 February 1962 have been analyzed to obtain the decrements of the level populations of hydrogen, the self-absorption in the Balmer lines, and parameters useful in construction of models of the low chromosphere. The decrement of the high energy levels of hydrogen inferred under the optically thin assumption does not vary significantly with height, and it appears to be unnecessary to seek large deviations from local thermodynamic equilibrium in the high levels. The observed Balmer-to-Paschen line intensity ratios have been used to infer self-absorption and opacities in the Balmer lines. The resulting population of the second energy level is about an order of magnitude smaller than that found by Athay and Thomas from the 1952 data. The chromospheric continuum was generally underexposed; the absence of observed continuum in the visible region of the spectrum made it impossible to derive a unique model from the 1962 data alone. However, the high Balmer line data and new theoretical solutions of the statistical equilibrium equations for hydrogen combined with corrected 1952 observations at λ 4700 A are compatible with a model having approximately the same temperature and neutral hydrogen structure as the 1952 model by Pottasch and Thomas but half the electron density: T e = 6200K, N 1 = 7.4 × 1013 cm-3, N e = 2.3 × 1011 cm-3 at 500 km and T e = 7200K, N 1 = 2.6 × 1012 cm-3, N e = 1.7 × 1011 cm-3 at 1000 km.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145729
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  • 4
    Electronic Resource
    Electronic Resource
    Discussion of a possible magnetic transient in UVSP observations (1986)
    Springer
    Solar physics 104 (1986), S. 359-362 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract As part of a search for possible magnetic transients in the transition region, polarization observations were made in the C iv line at 1548 Å during a flare on 1980, July 13. In contradiction to earlier informal reports, it is not possible to state that magnetic transients of several thousand gauss have really been detected. This conclusion is based primarily on the lack of correlation in the circular polarization signals observed in the two halves of the spectral line and also on the possible effects of rapid fluctuations of intensity, velocity, and line width and shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159088
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  • 5
    Electronic Resource
    Electronic Resource
    Absolute redshifts in the C iv 1548 Å line in the transition region of the quiet Sun (1992)
    Springer
    Solar physics 141 (1992), S. 51-63 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations with the UVSP instrument on the SMM spacecraft were made at the polar limb and disk center for the accurate determination of Doppler shifts of the Civ 1548 Å emission line formed at 105 K in the transition region of the quiet Sun. Individual data points representing 3 arc sec square pixels yield both redshifts and blueshifts, but the mean values from four different days of observations are toward the red. The mean redshifts are in the range 4–8 km s-1 and are produced by nearly vertically directed flows; the uncertainty associated with the mean values correspond to ±0.5 km s-1. The redshift increases with brightness of the Civ line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00155903
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  • 6
    Electronic Resource
    Electronic Resource
    On the chromospheric observations at the 1962 eclipse (1969)
    Springer
    Solar physics 9 (1969), S. 56-64 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A discussion is given of slitless spectrograms of the chromosphere obtained by an expedition of the High Altitude Observatory, Sacramento Peak Observatory, and National Bureau of Standards at the eclipse of 4–5 February 1962. The data which are considered consist of previously published line intensities plus continuum data presented here for the first time. The data reduction procedure is briefly reviewed and a source of error introduced during the reduction is described. The error can possibly affect many of the reported line intensities. Comparison of the 1962 observations with the HAO data from the 1952 eclipse indicates that the previously suggested factor-of-two decrease in the earlier data should be modified to a wavelength-dependent correction: a decrease by a factor of three or four at the high Balmer lines, a decrease by a factor of two at λ 4700 A, no change at Hα, and an increase by a factor of about 1.5 at the Paschen lines. The observed Balmer-to-Paschen line intensity ratios are therefore in the theoretically acceptable range, in contrast to the 1952 results. The height gradients of the Balmer line intensities agree reasonably well although the 1962 data tend to curve downward relative to a simple exponential distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145728
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of UVSP Dopplergrams and magnetograms and their calibration using the orbital velocity of the SMM spacecraft (1984)
    Springer
    Solar physics 92 (1984), S. 67-73 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract To infer velocities and longitudinal magnetic fields from Dopplergram and magnetogram signals obtained by the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission, one must know the width of the observed emission line. Although the instrument control system provided for a line-width calibration feature which utilized periodically commanded shifts of the line, it was not always used. However, it is possible to use the time-varying line-of-sight component of the orbital velocity of the spacecraft as a means of calibrating the line width for each pixel in a raster. Such a method based on a least-squares fit of the observed Doppler signal to the line-of-sight component of the spacecraft velocity is described here; it then applied to magnetogram observations. As background, the theoretical expressions for the interpretation of the observed Dopplergram and magnetogram signals for both wide and narrow exit slits are also summarized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157235
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  • 8
    Electronic Resource
    Electronic Resource
    Absolute flows in the solar transition region (1990)
    Springer
    Astrophysics and space science 170 (1990), S. 173-178 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is the objective of the present study to establish an absolute scale for flows in the solar transition region in observations obtained with the UVSP/SMM. By use of the polar limbs as reference one finds that the downflows range between 3 and 10 km s−1. The brighter regions show the largest downward flows.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652664
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