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  • 1
    Electronic Resource
    Electronic Resource
    Counter-streaming gas flows in solar prominences as evidence for vertical magnetic fields (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 396 (1998), S. 440-441 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Solar prominences are sheets of relatively cool and dense gas embedded in the surrounding hotter corona. An erupting prominence can inject a mass of up to 1015 g into the solar wind as part of a coronal mass ejection. These eruptions must depend critically on the topology ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/24798
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A search for the footpoints of solar magnetic fields (1974)
    Springer
    Solar physics 35 (1974), S. 331-342 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-resolution measurements of magnetic fields have been made in quiet and active regions in order to determine whether the photospheric fine-structures (‘crinkles’), recently photographed by Dunn (1972), coincide with the footpoints of strong, compact fields. Magnetic fields ranging up to 1400 G have been measured in small structures that lie at the centers of spicule bushes or within a plage. However, the diameters of the flux tubes, at the height where Fei 6302.5 forms, are typically 1″–2″, compared with crinkle dimensions of 0.25″ × 1″. This discrepancy cannot be explained by a sharp height variation of the flux tube cross-section. By comparing our results with Dunn's photographs, we conclude that although crinkles appear to lie at or near the strongest field intensities, photospheric magnetic flux is not confined solely within the area of the crinkles, but may extend over a larger area defined by the ‘abnormal’ granulation (Dunn et al., 1973; Dunn and Zirker, 1973).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151955
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The Sinistral–Dextral Regularity: An Independent Test (1997)
    Springer
    Solar physics 176 (1997), S. 279-283 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Leroy, Bommier, and Sahal-Bréchot (1984) determined the vector magnetic field in a large sample of quiescent prominences. The direction of the axial component is in general subject to a 180 deg uncertainty. We have selected those prominences in the sample whose field direction is unambiguous. For 95 such prominences, only 3 do not obey the hemispheric preferences of sinistral or dextral filaments, discovered by Martin, Tracadas, and Billamoria (1994). No explanation for the exceptional cases was found. A search of the Ottawa River Solar Observatory archives was made to check on the structural signatures of sinistral and dextral filaments. Of 32 filaments in common with the Leroy data set, 12 were classifiable as sinistral or dextral from their Hα fine structure and of these, 3 were exceptions to the hemispheric rule. Thus only a small percentage of quiescent filaments disobeys the hemispheric rule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004950821699
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A model for X-ray emission from loop prominences (1977)
    Springer
    Solar physics 53 (1977), S. 41-58 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A study is made of X-ray line emission observed during the developing stages of a set of post-flare loop prominences. The time behaviour of the line emission can be described by a model consisting of two flux tubes containing plasma heated impulsively at the flash phase; the plasma cools by radiation and by conduction to the chromosphere. These ideas are extended to the possible formation of Hα prominences from low-lying hot loops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260208
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    The anatomy of the Sun (1992)
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 552-552 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] OUR Sun proves the rule that the closer you look at anything in nature, the more complicated it becomes. For at least 40 years, astronomers have sought satisfac-tory explanations for some of the most obvious solar phenomena. Why does the Sun's equator rotate faster than its poles? Why is its ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/357552a0
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The interpretation of total line intensities from optically thin gases (1972)
    Springer
    Solar physics 22 (1972), S. 327-343 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The diagnostic method developed in the two preceding papers of this series is applied to coronal forbidden line intensity data obtained at eclipses in 1952, 1961, 1965, 1966, and 1970. The application of the method is limited by the nature of the data but allows a first inference of the relationship between electron density and temperature in the condensations observed at these eclipses, and of the distribution of the electrons within the temperature range samples by the observations effectively 106 to 2.4 × 106 K. We determine the relative abundance of nickel to iron in the corona, finding a value in agreement with latest photospheric determinations and with a similar (factor of two) uncertainty. We are also able to set lower limits to the abundance of iron with respect to hydrogen, again finding values consistent with recent photospheric determinations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148700
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  • 7
    Electronic Resource
    Electronic Resource
    The interpretation of total line intensities from optically thin gases (1972)
    Springer
    Solar physics 22 (1972), S. 317-326 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss the application of a general diagnostic procedure, developed in the preceding paper of this series, to the inference of the physical state of coronal condensations from a knowledge of their forbidden line emission. We consider the limitations set on such an analysis by inadequacies in existing data and indicate the additional observations in the infrared and ultraviolet, as well as the visible, which will be needed for development of the full power of the diagnostic method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148699
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  • 8
    Electronic Resource
    Electronic Resource
    The interpretation of total line intensities from optically thin gases (1972)
    Springer
    Solar physics 22 (1972), S. 307-316 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a general method for inferring, from the line emission of an optically thin medium, the physical state of the gas along the column in the line of sight which is sampled by the observations. Since it is not possible to infer the distribution of the physical state parameters with position in the line of sight - any arbitrary rearrangement of material giving equivalent line emission - we seek instead to specify the state in another way. A unique specification is found in terms of the bivariate distribution function μ (n, T), describing the partitioning of the matter in the gas over the density and temperature. We show that, given sufficient observational data, it is in principle possible to determine both μ (n, T), and the chemical composition. With less complete data the acuity of the analysis is correspondingly reduced. The method is devised for application to the astronomical case, especially for studies of the solar corona, the chromosphere-corona transition region, planetary nebulae and other optically thin sources. We illustrate the formulation for the situation encountered in the solar corona.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148698
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    The excitation equilibrium of coronal ions (1970)
    Springer
    Solar physics 11 (1970), S. 68-81 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The relative populations of levels of highly ionized Fe, Ni and Ca ions have been calculated for physical conditions appropriate to the solar corona. The results are presented in the form of tables. Line intensity ratios in the EUV and visible that are sensitive to electron density are discussed and compared with observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156552
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  • 10
    Electronic Resource
    Electronic Resource
    Coronal heating (1993)
    Springer
    Solar physics 148 (1993), S. 43-60 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The prospects for observational tests of coronal heating theories are examined. Three heating mechanisms (Alfvén waves, D.C. electric currents, and MHD turbulence) are reviewed from this point of view. Some suggestions are offered for future tests but none, so far, would give unambiguous critical results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00675534
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    Paper (German National Licenses)
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