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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic field measurements based on the Zeeman splitting of forbidden transitions (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 855-856 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The measurement of the poloidal magnetic field in a tokamak plasma from the Zeeman splitting and polarization of the magnetic dipole radiation from heavy ions is discussed. When viewed from a direction perpendicular to the toroidal field, the effect of the poloidal field on the circularly polarized radiation is detectable using a photoelectric polarimeter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138071
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  • 2
    Electronic Resource
    Electronic Resource
    Large-scale coronal heating by the small-scale magnetic field of the Sun (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 394 (1998), S. 152-154 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Magnetic fields play a crucial role in heating the outer atmospheres of the Sun and Sun-like stars, but the mechanisms by which magnetic energy in the photosphere is converted to thermal energy in the corona remain unclear. Observations show that magnetic fields emerge onto the solar surface as ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/28108
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  • 3
    Electronic Resource
    Electronic Resource
    Solar gradual hard X-ray bursts: Observations and an interpretation
    Amsterdam : Elsevier
    Advances in Space Research 6 (1986), S. 249-252 
    Details
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0273-1177(86)90154-7
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of newly erupting flux on the polar coronal holes (1989)
    Springer
    Solar physics 119 (1989), S. 323-340 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract He i 10830 Å images show that early in sunspot cycles 21 and 22, large bipolar magnetic regions strongly affected the boundaries of the nearby polar coronal holes. East of each eruption, the hole boundary immediately contracted poleward, leaving a band of enhanced helium network. West of the eruption, the boundary remained diffuse and gradually expanded equatorward into the leading, like-polarity part of the bipolar magnetic region. Comparisons between these observations and simulations based on a current-free coronal model suggest that: (1) The Sun's polar magnetic fields are confined to relatively small caps of high average field strength, apparently by a poleward meridional flow. (2) The enhanced helium network at high latitude marks the location of relatively strong polar fields that have become linked to the newly erupted bipolar region in that hemisphere. (3) The distortion of the polar-hole boundary is accompanied by a corresponding distortion of the equatorial neutral sheet in the outer corona, in which the amount of warping depends on the magnitude of the erupted flux relative to the strength of the Sun's polar magnetic fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146182
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  • 5
    Electronic Resource
    Electronic Resource
    Observations of small-scale solar magnetic fields (1967)
    Springer
    Solar physics 1 (1967), S. 171-179 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spectrograms, obtained during moments of good seeing with the high spatial resolution afforded by the 80-cm solar image at the Kitt Peak National Observatory, show the following: (1) Magnetic fields of several hundred gauss occur in tiny areas easily as small as 500 km in extent in regions of the solar surface sometimes well removed from areas of sunspot activity. (2) In these tiny areas of magnetic field, many Fraunhofer lines seem to be weakened, appearing on spectrograms as discontinuities or gaps in the absorption lines. (3) Although the small-scale magnetic fields are manifested by local weakenings of many absorption lines, these fields often correspond to local darkenings in the continuum, suggesting that the small-scale fields often occur in the dark lanes and pores of the granulation. (4) These tiny areas of relatively strong magnetic field correspond to regions of bright Ca+ K232 emission, not to the so-called K2V bright points seen on spectroheliograms. It is implied that these relatively strong fields associated with the weakenings or gaps in Fraunhofer lines are precisely the fields detected using Leighton's photographic technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00150852
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  • 6
    Electronic Resource
    Electronic Resource
    Properties of metre-wavelength solar bursts associated with coronal mass ejections (1986)
    Springer
    Solar physics 105 (1986), S. 149-171 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An investigation is made to determine the relationship between a coronal mass ejection (CME) and the characteristics of associated metre-wave activity. It is found that (1) the CME width and leading edge velocity can be highly influential in determining the intensity, spectral complexity and frequency coverage of both type II and continuum bursts; (2) the presence of a CME is possibly a necessary condition for the production of a metric continuum event and (3) metric continuum bursts as well as intense, complex type II events are preferentially associated with strong, long lasting soft X-ray events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00156384
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  • 7
    Electronic Resource
    Electronic Resource
    Coronal holes, solar wind streams, and recurrent geomagnetic disturbances: 1973–1976 (1976)
    Springer
    Solar physics 49 (1976), S. 271-278 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of coronal holes, solar wind streams, and geomagnetic disturbances during 1973–1976 are compared in a 27-day pictorial format which shows their long-term evolution. The results leave little doubt that coronal holes are related to the high-speed streams and their associated recurrent geomagnetic disturbances. In particular, these observations strongly support the hypothesis that coronal holes are the solar origin of the high-speed streams observed in the solar wind near the ecliptic plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162451
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  • 8
    Electronic Resource
    Electronic Resource
    A comparison of He ii 304 Å and He i 10 830 Å spectroheliograms (1977)
    Springer
    Solar physics 54 (1977), S. 343-351 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Spectroheliograms were obtained simultaneously in the He ii 304 Å emission line and the He i 10 830 Å absorption line with an angular resolution of approximately 5″. A negative print of the 304 Å image is matched with a positive print of the 10 830 Å image so that corresponding features of the chromospheric network (including active regions) appear identical in the two images. Differences between these images include the facts that: (1) Disk filaments and limb darkening are strongly visible in the 10 830 Å positive image, but they are weakly visible (as lightenings) in the 304 Å negative image. (2) The contrast between the chromospheric network and the network cell centers is much greater in the 10 830 Å image than in the 304 Å negative image. These results provide constraints on models of helium line formation in various types of solar features.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159924
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  • 9
    Electronic Resource
    Electronic Resource
    Extreme ultraviolet observations of coronal holes (1978)
    Springer
    Solar physics 56 (1978), S. 125-151 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Extreme-ultraviolet Skylab and ground-based solar magnetic field data have been combined to study the origin and evolution of coronal holes. It is shown that holes exist only within the large-scale unipolar magnetic cells into which the solar surface is divided at any given time. A well-defined boundary zone usually exists between the edge of a hole and the neutral line which marks the edge of its magnetic cell. This boundary zone is the region across which a cell is connected by magnetic arcades with adjacent cells of opposite polarity. Three pieces of observational evidence are offered to support the hypothesis that the magnetic lines of force from a hole are open. Kitt Peak magnetograms are used to show that, at least on a relative scale, the average field strengths within holes are quite variable, but indistinguishable from the field strengths in other quiet parts of the Sun's surface. Finally it is shown that the large, equatorial holes characteristic of the declining phase of the last solar cycle during Skylab (1973–74) were all formed as a result of the mergence of bipolar magnetic regions (BMR's), confirming an earlier hypothesis by Timothy et al. (1975). Systematic application of this model to the different aspects of the solar cycle correctly predicts the occurrence of both large, equatorial coronal holes (the ‘M-regions’ which cause recurrent geomagnetic storms) and the polar cap holes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152639
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  • 10
    Electronic Resource
    Electronic Resource
    The equatorward extent of auroral activity during 1973–1974 (1978)
    Springer
    Solar physics 58 (1978), S. 405-422 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The equatorward boundary of auroral activity during 1973–1974 has been derived from DMSP photographs and their associated ‘auroral analysis records’. On a time scale of days, the equatorward position of the northern auroral oval varied in phase with the average level of geomagnetic activity. In general, this variation was associated with the occurrence of solar flares and coronal holes. On a time scale of hours, the equatorward position of the oval correlated with the AE index of substorm activity and with the strength of the southward component of the interplanetary magnetic field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157285
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