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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 35 (1974), S. 331-342 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 3 (1968), S. 269-281 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The discussion of the Hα double limb had reached the point where the question of its existence as a real solar phenomenon could not be resolved without new observations made with the Lockheed filter and the Mount Wilson spectroheliograph. A study of the instrumental profiles had indicated that there was sufficient off-band light to produce the observed inner limb step in the Mount Wilson instrument, but this analysis was not completely satisfactory because of limitations inherent in the measurement of instrument functions with a Hg-198 source. The instrumental profile work did indicate, however, that the spectral purity of the instruments in question could be substantially improved by the use of narrow-band interference filters. An experimental program was thus launched to determine the effect of such a blocking filter on the appearance of the Hα limb. The results of these observations with three Halle filter systems and the Mount Wilson spectroheliograph are that the inner limb completely disappears at the center of Hα when a blocking filter is used to reduce unwanted light, which originates at wavelengths beyond ±0.8 Å. In addition, the contrast and visibility of the chromospheric fine structure is increased by eliminating the off-band light. Thus the experiment conclusively demonstrates that the apparent inner limb is not a solar feature but is due entirely to instrumental parasitic light.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 87 (1983), S. 65-75 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Known potential field solutions can be used to model the structure of magnetic fields in the solar photosphere. Several two-dimensional and axisymmetric solutions are compared. In the most satisfactory model the vertical component of the field is prescribed on a horizontal plane so as to be uniform within a finite disc and zero outside it. The resulting flux distribution provides a good description of small scale intergranular magnetic fields and of the observed field structure in a pore, but is inadequate for sunspots.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 2 (1849), S. 331-333 
    ISSN: 1432-2307
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 13 (1970), S. 85-103 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The magnetic field in an axisymmetric pore is current free and can be represented by a flux tube with a magnetic potential of the formAJ 0(kr)e -kz. For a given magnetic flux the field in this pore model is uniquely defined if the magnetic pressure balances the gas pressure at two levels. For models with fluxes of 0.5–3.0 × 1020 mx the surface radius varies from 1100–2700 km (diameters of 3–8 arc-sec) and the Wilson depression is estimated at 200 km. As the flux increases, the field becomes nearly horizontal at the edge of the pore and eventually a penumbra is formed. The distinction between pores and sunspots is investigated; the critical flux is about 1020 Mx, corresponding to a radius of 1500 km.
    Type of Medium: Electronic Resource
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