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  • 1980-1984  (4)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Long time delay between the peaks of intense solar hard X-ray and microwave bursts (1983)
    Springer
    Solar physics 89 (1983), S. 379-390 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the long time delays more than five seconds between the peaks of intense hard X-ray and microwave bursts are concerned with two independent phenomena. One is the energy dependent time delays in X-rays and the other is the frequency dependent time delays in microwaves. The time delays of 5 s to 10 s between the peaks of solar hard X-ray burst (≲100 keV) obtained with Hinotori spacecraft and microwave burst at 17 GHz were observed exceptionally in three intense events with a spectral maximum at about 17 GHz. It is found that the peak of harder X-rays (≳300 keV) also delays in these events by about the same amount with respect to the softer X-rays (≲100 keV), so that the peak at 17 GHz nearly coincides (≲4s) with that of the harder X-rays. This is quite reasonable because the gyro-synchrotron emissions from the electrons below about 100 keV in the solar flares are generally negligible at high microwave frequencies (≳10 GHz). The optical thickness of the radio source decreases with frequency and is unity generally at about 10–20 GHz in intense bursts as inferred from the radio spectrum. Further delay of the peaks at the lower microwave frequencies is attributed to the temporal increase in the effective size of radio source which is optically thick at the lower frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217257
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Source structure of gradual rise and fall bursts at 17 GHz (1982)
    Springer
    Solar physics 78 (1982), S. 243-252 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract From ∼ 200 GRF (gradual rise and fall) bursts which have been recorded with the 17 GHz interferometer at Nobeyama, we deduce the following characteristics of GRF bursts: (1) Sources of GRF bursts are broader, less circularly polarized than those of impulsive bursts. (2) The sources are potentially of bipolar structure and have the peak brightness near the position at which the sense of circular polarization changes. (3) The association of GRF bursts with type III bursts, which are indicative of nonthermal electron acceleration, is significantly poorer than that of impulsive bursts. It is suggested that the sources of GRF bursts or generally of thermal bursts lie relatively high in the solar atmosphere possibly near the top of magnetic loops or arches which divide two regions of opposite magnetic polarity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151607
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Late phase gradual enhancements in microwaves and hard X-rays of the 6 November 1980 flare (1983)
    Springer
    Solar physics 86 (1983), S. 231-236 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Gradual enhancements which repeatedly appeared 20–50 min after the onset of an impulsive burst were observed in microwaves and hard X-rays. The observed characteristics of the gradual enhancements are (i) the similarity of time profiles in both the frequency range of 17 GHz to 160 MHz and the energy range of 40 to ∼400 keV, (ii) the low peak frequency of the microwave spectrum (∼4 GHz), and (iii) the flat X-ray spectrum with the power-law exponent of ∼1.7. It is suggested that the radio and X-ray gradual enhancements are due to a single population of energetic electrons which extend high in the corona (at least 1.4 × 105 km). Nevertheless the 17 GHz source is likely to be at a low altitude, not much higher than the preceding impulsive burst source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00157193
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Successive electron and ion accelerations in impulsive solar flares on 7 and 21 June 1980 (1983)
    [s.l.] : Nature Publishing Group
    Nature 305 (1983), S. 292-294 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The time profiles of the impulsive burst on 7 June are shown in Fig. 1. The burst is composed of seven successive pulses of a quasiperiodicity of 8 s, for each of which the hard X-ray, ?-ray and microwave emissions were observed almost simultaneously1"6. Hard X-ray and ?-ray observations were made ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/305292a0
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    Paper (German National Licenses)
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