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  • 1
    Electronic Resource
    Electronic Resource
    An empirical, statistical model for the formation of the cores of chromospheric Fraunhofer lines (1977)
    Springer
    Solar physics 54 (1977), S. 3-24 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe an empirical, statistical model for the formation of the cores of chromospheric Fraunhofer lines. The model chromosphere consists of brighter structural elements with large scale motions randomly distributed in space, and above these, darker structural elements, again randomly distributed in space. Both components overlie a more uniform lower chromosphere. The probability of finding a given number of elements along a line of sight is specified by a Poisson distribution, in terms of the average number of structures along the line of sight. When this average is small, the statistical model may behave like an effectively thin plane-parallel chromosphere, even when the optical thickness of the individual structures is very large. The model has been applied to the interpretation of Ca ii and Mg ii resonance lines, and to Hα and Hβ. By comparing computed mean intensity profiles and profiles associated with statistical intensity fluctuations with observations, a consistent set of chromospheric parameters was determined. It is tentatively concluded that the line cores are formed by structural elements whose optical thicknesses are very large at the line centre of K, located somewhere not far above 1000 km and moving with RMS velocity of about 7 km s−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146419
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Bright threads in the inner wing of solar Ca II K line (1987)
    Springer
    Solar physics 112 (1987), S. 59-66 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract On spectrograms of the K line at quiet regions of the Sun, bright threads visible in the real continuum due to the granulations are also seen in the outer wing as far as ¦Δλ¦ ∼ 3 Å from the line centre. At the inner wing (3 Å ≳ ¦Δλ¦ ≳ 0.5 Å) bright threads are also seen, but their spatial distribution is different from the former ones. The threads at the inner wing appear at intergranular regions, and many of them are seen inside the supergranulation. Their size and number density are about the same as those of the granulation. These facts reflect that the penetration of the granular high temperature layer stops at a certain height in the photosphere, and that the intergranular bright threads at the inner wing are due to a hotter temperature layer, located at a considerably higher photospheric layer than the granulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148487
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Continuous and line spectra of granules and intergranular lanes (1990)
    Springer
    Solar physics 127 (1990), S. 11-27 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Temperature and velocity structures above granules and intergranular lanes were studied on spectrograms covering Caii H and K lines. In agreement with our earlier results, it was confirmed more quantitatively that there appear two kinds of bright continua, one in the outer wings (granular continuum) and the other in the inner wings (temporarily called K0-continuum) of Caii H and K lines, and that these two kinds of bright continua are located more or less in a complementary fashion. Further, it was found that the bright K0-continuum is well associated with higher central residual intensity of absorption lines. These facts suggest that in the upper photosphere of, say, τ 〈 0.1, there are high temperature regions in the intergranular lanes. Motions above granular regions are essentially upwards, whereas those of intergranular regions are predominantly downwards, and in the uppermost photosphere the motions become more random.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158511
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A measurement of the solar H and K profiles (1968)
    Springer
    Solar physics 3 (1968), S. 523-530 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new series of photometric observations of the H and K lines were obtained at Sacramento Peak Observatory in 1964 and 1965. In both the observations and the data reduction special attention was given to obtaining a suitable average over the solar fine structure and to defining a proper reference continuum. The results are that the central intensities of H and K are the same and equal to 4.2% of the continuum. The limb-darkening curves at the line centres are also the same for both lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151934
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    Paper (German National Licenses)
    Fulltext
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