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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 396 (1998), S. 440-441 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 119 (1989), S. 341-356 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This review surveys recent research on quiescent solar prominences. The main topics considered are magnetic structure, thermal structure, and formation. Sub-arc sec fine-structures undoubtedly play a crucial role in all three topics. Current attempts to model the magnetic and thermal structure are hampered, in part, by the lack of observations with sufficient spatial resolution. The process of formation is quite complicated, but is yielding slowly to detailed numerical simulations. Unfortunately, observations of prominence ‘condensation’ from the corona (the favored hypothesis) are lacking. Some suggestions for future work are offered.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 11 (1970), S. 68-81 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 16 (1971), S. 103-110 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A series of spectrograms of the inner solar corona were obtained at the total solar eclipse of 30 May 1965 using a fast spectrograph with a circular slit that recorded the spectrum from λ3000 to λ9000 at all position angles around the limb simultaneously. In this paper absolute intensity is given as a function of position angle for the stronger lines and the continuum. In the coronal enhancement or condensation centered at heliocentric position angle 293°, absolute intensity is given for 34 forbidden emission lines and the continuum.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 144 (1993), S. 341-347 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this paper we will show that the twisting mechanism of Sturrock and Uchida is as viable a heating source for the active corona as Parker's braiding. This conclusion contradicts that of Berger (1990). Moreover, we shall show that if we adopt Berger's criterion for reconnection, braiding produces far more flare energy than is observed. A modified criterion, consistent with twisting, produces insufficient heating but, coupled to an avalanche process, could account for active region flares.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 175 (1997), S. 27-44 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During the past five years at least six manifestations of a global organization of solar magnetic fields have been recognized. The magnetic chirality (handedness) of the following features shows a hemispheric preference: filament channels, quiescent filaments, sunspot whorls, superpenumbral fibrils, coronal arcades, and interplanetary clouds associated with CMEs. Although the patterns are clear in the data, their interpretation and their possible connection to the dynamo is open to question. This paper reviews the observations of the patterns, corrects some misinterpretations, and offers a scenario for the origin of the most marked pattern, the chirality of filaments. We suggest the pattern arises from the reconnection of coronal loops, under the influence of supergranulation and differential rotation. Unlike alternative scenarios, ours relies only on observable surface motions and fields.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 22 (1972), S. 327-343 
    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
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 22 (1972), S. 307-316 
    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
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 53 (1977), S. 41-58 
    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
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  • 10
    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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