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  • 1975-1979  (1)
  • 1965-1969  (14)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    The intensity, velocity and magnetic structure of a sunspot region (1968)
    Springer
    Solar physics 4 (1968), S. 142-164 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The observational set-up for a detailed study of the velocity, intensity and magnetic-field fine structure in and around a sunspot is described. On highly resolved spectra we detected in the vicinity of a sunspot a large number of points with strong magnetic fields (magnetic knots). The magnetic field in these knots causes a striking decrease of the line depth (or a ‘line gap’ after Sheeley, 1967). The properties of the magnetic knots are: (1) magnetic fields up to 1400 gauss; (2) diameter ≈ 1100 km; (3) coincidence with dark intergranular spaces; (4) generally downward material motion; (5) lifetime〉30min; (6) estimated total number around an unipolar spot ⩾ 2000; (7) combined magnetic flux comparable to the sunspot flux; (8) coincidence with Ca+ plages. For the smallest sunspots (pores) we obtained magnetic fields 〉1500 gauss. Hence a magnetic field of about 1400–1500 gauss appears to be a rather critical level for pore and spot formation. We found a large number of small areas producing line gaps without measurable magnetic field. These ‘non-magnetic gap-regions’ coincide with bright continuum structures. Some aspects arising from the occurrence of hundreds of magnetic knots in an active region are discussed in the last section.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148076
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The interpretation of velocity filtergrams (1969)
    Springer
    Solar physics 9 (1969), S. 35-38 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The paper describes a numerical experiment in which the effect of an assumed velocity distribution in the solar atmosphere on the intensity difference between a blue- and a red-wing filter-gram is derived. This results in the effective optical depth at which the velocity is measured. It is shown that this τeff strongly depends on the assumed velocity distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145725
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    On the relation between the photospheric intensity, velocity and magnetic fields (1968)
    Springer
    Solar physics 4 (1968), S. 165-167 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148077
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The intensity, velocity and magnetic structure of a sunspot region (1968)
    Springer
    Solar physics 4 (1968), S. 303-314 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A time sequence of high-resolution sunspot photographs, exposed almost simultaneously in two continuum wavelengths (4680 Å and 6400 Å), was used to study some properties of umbral fine structures (‘umbral dots’). The lifetime of the umbral dots is found to be 1500 sec. Photometry of some bright dots leads to an observed intensity excess of 0.129 I phot and 0.134 I phot in the blue and red respectively. The observed mean diameter of the dots is found to be 420 km. These values still include the action of image blurring. From the color index the true intensity and diameter of the dots are estimated. It appears that the umbral dots are in reality of photospheric brightness having true diameters of 150–200 km. The spatial distribution of the dots in sunspot umbrae is discussed. Some peculiarities in recent sunspot magnetic-field observations may be explained by magnetic inhomogeneities associated with umbral dots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149561
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Report on the solar physics-plasma physics workshop (1976)
    Springer
    Solar physics 46 (1976), S. 411-431 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This report summarizes the proceedings of a meeting held on 17–20 September 1974, at Stanford University. The purpose was to explore plasma physics problems which arise in the study of solar physics. Sessions were concerned with specific questions including the following: Is the solar plasma thermal or non-thermal? What spectroscopic data are required? What types of magnetic field structures exist? Do MHD instabilities occur? Do resistive or non-MHD instabilities occur? What mechanisms of particle acceleration have been proposed? What information do we have concerning shock waves? Very few questions were answered categorically but, for each question, there was discussion concerning the observational evidence, theoretical analyses, and existing or potential laboratory and numerical experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149863
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The profiles of fraunhofer lines in the presence of zeeman splitting (1969)
    Springer
    Solar physics 9 (1969), S. 372-386 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract For the case of pure absorption lines (LTE) a method is described which enables the general computation of Zeeman-split line profiles. The magnetic field vector, the Doppler shift and the line absorption coefficient is permitted to vary arbitrarily with optical depth. Elliptical birefringence (e.g., Faraday rotation) of the solar atmosphere is taken into account. Some numerical examples are given and some interesting behaviors of the line profiles are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02391659
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Solar magnetic-field measurements using Babinet compensators (1969)
    Springer
    Solar physics 6 (1969), S. 480-481 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146482
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    The intensity, velocity and magnetic structure of a sunspot region (1969)
    Springer
    Solar physics 7 (1969), S. 22-25 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148400
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    The intensity, velocity and magnetic structure of a sunspot region (1969)
    Springer
    Solar physics 10 (1969), S. 384-403 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract From an investigation of spectra in a magnetically sensitive (λ 6173, g = 2.5) and insensitive line (λ 5576, g = 0), we derived the following properties for a symmetrical sunspot: (a) The magnetic field strength varies with the distance ρ(ρ ⩽ 1) from the sunspot center like H(ρ) = H(0) (1 + ρ 2)-1 (b) The zenith angle of the magnetic field varies like 90°ρ. From this and from H(ρ) we find a height gradient of 0.5 gs/km at ρ = 0. (c) The equivalent width and the half width of λ 5576 show an increase in penumbral regions of maximum Evershed flow. Most likely this is due to a combination of inhomogeneities in the Evershed flow and ‘microturbulence’. (d) We find the magnetic field strength to be larger in the dark interfilamentary regions of the penumbra. These regions move downwards with respect to the bright filaments and probably have a more horizontal magnetic field. (e) In a weak light bridge and in extensions of bright penumbral filaments into the umbra, we find a decrease of the magnetic field strength, and a more horizontal field direction with respect to the umbral surrounding. li(f)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145526
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  • 10
    Electronic Resource
    Electronic Resource
    The profiles of fraunhofer lines in the presence of Zeeman splitting (1969)
    Springer
    Solar physics 10 (1969), S. 262-267 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The radiative transfer equations (LTE) in the four Stokes parameters are derived for the general case of a Zeeman multiplet for both electric and magnetic dipole as well as for electric quadrupole radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00145513
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    Paper (German National Licenses)
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