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  • 1
    Electronic Resource
    Electronic Resource
    High Spatial Resolution Solar Microwave Observations (1982)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 20 (1982), S. 497-516 
    Details
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.aa.20.090182.002433
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  • 2
    Electronic Resource
    Electronic Resource
    An exceptionally bright flare from SGR 1806–20 and the origins of short-duration γ-ray bursts (2005)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 434 (2005), S. 1098-1103 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Soft-γ-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature03519
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  • 3
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    Sixty Years of "Jane's" (1958)
    London : Periodicals Archive Online (PAO)
    The RUSI journal. 103 (1958:May) 223 
    Details
    ISSN: 0307-1847
    Topics: Political Science
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:p225-1958-103-00-000033
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  • 4
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    Unknown
    The Royal Naval Reserve (1959)
    London : Periodicals Archive Online (PAO)
    The RUSI journal. 104 (1959:Nov.) 497 
    Details
    ISSN: 0307-1847
    Topics: Political Science
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:p225-1959-104-00-000072
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  • 5
    Electronic Resource
    Electronic Resource
    Microwave spectroscopy as a diagnostic of solar flares: The effect of source inhomogeneity (1982)
    Springer
    Solar physics 113 (1982), S. 183-185 
    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/BF00147696
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  • 6
    Electronic Resource
    Electronic Resource
    Gamma-ray and hard X-ray imaging of solar flares (1988)
    Springer
    Solar physics 118 (1988), S. 269-290 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss the scientific and technical aspects of high-resolution γ-ray and X-ray imaging of solar flares. The scientific necessity for imaging observations of solar flares and the implications of future observations for the study of solar flare electrons and ions are considered. Performance parameters for a future hard X-ray and γ-ray imager are then summarized. We briefly survey techniques for high-energy photon imaging including direct collimation imaging, coded apertures, and modulation collimators. We then discuss in detail the technique of Fourier-transform imaging. The basic formalism is presented, followed by a discussion of several practical aspects of the technique. We conclude our discussion of imaging techniques with a description of the options for detectors and grid fabrication. Several planned future high-energy imagers are described including the Solar-A hard X-ray imager, the balloon-borne GRID γ-ray imager, and the Pinhole/Occulter Facility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148596
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  • 7
    Electronic Resource
    Electronic Resource
    High-resolution microwave spectra of solar bursts (1989)
    Springer
    Solar physics 120 (1989), S. 351-368 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Microwave observations with exceptionally high spectral resolution are described for a set of 49 solar flares observed between May and October 1981. Total power data were obtained at 40 frequencies between 1 and 18 GHz by the Owens Valley frequency-agile interferometer with 10 s time resolution. Statistical analysis of this sample of microwave bursts established the following significant characteristics of their microwave spectra: (i) Most (≈ 80%) of the microwave events displayed complex spectra consisting of more than one component during some or all of their lifetime. Single spectral component bursts are rare. It is shown that the presence of more than one component can lead to significant errors when data with low spectral resolution are used to determine the low-side spectral index. (ii) The high-resolution data show that many bursts have a low-side spectral index that is larger than the maximum value of about 3 that might be expected from theory. Possible explanations include the effect of the underlying active region on the perceived burst spectrum and/or the necessity for more accurate calculations for bursts with low effective temperatures, (iii) the peak frequencies of the bursts are remarkably constant during their lifetimes. This is contrary to expectations based on simple models in which the source size and ambient field remain constant during the evolution of a burst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00159884
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  • 8
    Electronic Resource
    Electronic Resource
    The secondary spectral component of solar microwave bursts (1990)
    Springer
    Solar physics 125 (1990), S. 343-357 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Microwave observations in the range 1 to 18 GHz with high spectral resolution (40 frequencies) have shown that many events display a complex microwave spectrum. From a set of 14 events with two or more spectral components, we find that two different classes of complex events can be distinguished. The first group (4 events) is characterized by a different temporal evolution of the spectral components, resulting in a change of the spectral shape. These events probably can be explained by gyrosynchrotron emission from two or more individual sources. The second class (10 events) has a constant spectral shape, so that the two spectral components vary together in intensity. For all ten events in this second class, the ratio of primary to secondary peak frequencies is remarkably similar, exhibiting an average value of 3.4, and both components show a common circular polarization. These properties suggest either a common source for the different spectral components or several sources which are closely coupled. An additional example of this class of burst was observed interferometrically to provide spatial resolution. This event suggests that the primary and secondary components have a similar location, but that the surface area of the secondary component is larger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158411
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  • 9
    Electronic Resource
    Electronic Resource
    Microwave emission from a sunspot (1993)
    Springer
    Solar physics 144 (1993), S. 349-360 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A series of microwave observations of a sunspot in the active region NOAA 4741 was made with the Owens Valley Solar Array for the purpose of investigating the center-to-limb variation of both the spectral and spatial brightness distribution. In this investigation, several properties of the sunspot microwave radiation are found. First, sunspot microwave emission appears in two typical profiles depending on the heliocentric position of the spot: either the ring structure near disk center or single-peak structure near the limb. Second, the brightness temperature at high, optically thin frequencies (〉6 GHz) increases slightly as the spot approaches the limb, which we interpret as being due to the increase of the gyroresonance opacity of the field lines near the spot center as they gain greater viewing angles. Third, the center-to-limb variation of the gyroresonance spectrum seems to be mostly characterized by a change of effective harmonic, which accompanies a discontinuous change of the degree of polarization. Fourth, a change of spectrum from gyroresonance to free-free emission is found in the passage of the spot over the solar limb, which gives a determination of the height of the gyroresonance layer to confirm its location low in the corona of the active region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627599
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  • 10
    Electronic Resource
    Electronic Resource
    Multiple energetic injections in a strong spike-like solar burst (1984)
    Springer
    Solar physics 91 (1984), S. 359-376 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An intense and fast spike-like solar burst was observed with high sensitivity in microwaves and hard X-rays, on December 18,1980, at 19h21m20s UT. It is shown that the burst was built up of short time scale structures superimposed on an underlying gradual emission, the time evolution of which showed remarkable proportionality between hard X-ray and microwave fluxes. The finer time structures were best defined at mm-microwaves. At the peak of the event the finer structures repeat every 30–60 ms (displaying an equivalent repetition rate of 16–20 s-1). The more slowly varying component with a time scale of about 1 s was identified in microwaves and hard X-rays throughout the burst duration. Similarly to what has been found for mm-microwave burst emission, we suggest that X-ray fluxes might also be proportional to the repetition rate of basic units of energy injection (quasi-quantized). We estimate that one such injection produces a pulse of hard X-ray photons with about 4 × 1021 erg, for ɛ ⪞ 25 keV. We use this figure to estimate the relevant parameters of one primary energy release site both in the case where hard X-rays are produced primarily by thick-target bremsstrahlung, and when they are purely thermal, and also discuss the relation of this figure to global energy considerations. We find, in particular, that a thick-target interpretation only becomes possible if individual pulses have durations larger than 0.2 s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146305
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