Solar bursts at λ = 2 cm on July 31, 1972

Castelli, J. P.; Guidice, D. A.; Forrest, D. J.; Babcock, R. R.

doi:10.1029/ja079i007p00889

Cited by 10 publications

(1 citation statement)

References 14 publications

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“…Taking B = 2800 G after Castelli et al (1974), we find For the September 8 event, the local Alfven speed is ti 3.5 x 10 3 km s-1 and the temporal separation b.stween phases a and b is ti 12 s; substitution of these values for V 1 and At into Equation 3 yields a source separation of A about 4.2 x 10 4 kin. According to Equation 6, the magnetic-field strengths of > 240 and ti 75 C found for the sources in phases a and b imply a vertical source separation of Ah > 3.7 x 10 4 kin, which is comparable to the first estimate.…”

Section: Discuss1un and Cunclusiun:-mentioning

confidence: 96%

Spectral evolution of multiply impulsive solar bursts

Karpen

Crannell

Frost

1979

ApJ

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Hard X-ray and microwave observations of multiply-impulsive solar bursts, identified in the OSO-S data, have been analyzed in a search for the physical basis of the multiplicity of spikes within these events. Spectra in both frequency ranges have been used to determine whether or not the source p roperties change from peak to peak within individual bursts. Two categories of microwave spectral behaviour have been identified: those events during which the microwave turnover frequency and spectral shape remain the same from peak to peak, and those during which the turnover f.ret.uei,cy and spectral shape change significantly.1'liese categories correspond to two classes of multiply-impulsive bursts: those fc;r which the emission can be characterized by a constant magnetic field and therefore a single source region, in which case the multiplicity may be due to modulation of the emission process; and those in which groups of component spikes appear to originate in regions of different magnetic-field strengths, corresponding to separate source regions which flare sequentially. Examples of the latter type of events are presented, with a detailed analysis of the discrete flaring regions and estimates of their spatial separations.

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Section: Discuss1un and Cunclusiun:-mentioning

confidence: 96%

Spectral evolution of multiply impulsive solar bursts

Karpen

Crannell

Frost

1979

ApJ

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A comparison of the optical and microwave emissions of some major solar flares

Roy

1979

Sol Phys

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In the first part of the paper, we study the relations between the frequency of maximum radio flux f,n~, and the magnetic field strength at the photosphere B o and between the maximum radio flux Fmax and the field and its scale L for two differing flares occurring above very different photospheric conditions. It is shown that the simple relations predicted by the gyro-synchrotron emission mechanism [,,a~ ~ Bp and Fm~x ~ B2L 2 account for the fact that the flares produced microwave bursts of about the same Fmax, but of differing f m~,.The spectra of type IVp. radio bursts associated with three large proton flares with post-flare loops have been analyzed. It is found that the decimetric peak vanishes with the onset of the first optical loops. This is consistent with the model of Kopp and Pneuman (1976) which associates growing systems of loops with gradual fieldline reconnection above flaring regions.

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Spectral distributions of microwave bursts

Guidice

Castelli

1975

Sol Phys

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The lack of open literature publication of the distributional properties of the cm-2 spectra of solar microwave bursts has lead to some erroneous concepts of the typical characteristics of these spectra. To provide more accurate information, this paper sets forth various distributions of the peak flux density spectra of large numbers of bursts, based on observations of the Sagamore Hill Radio Observatory at nine discrete frequencies between 245 and 35000 MHz over the years 1968-1971. As a foundation for the distribution studies, the basic spectral classification system is outlined. The majority of burst spectra were found to contain a cm-2 component having a single spectral maximum in the 1400 to 35000 MHz range; such spectra are designated C type. A study of the correlation of the spectral maximum frequency fm~x of the cm component and the photospheric magnetic field strength of the associated region shows a tendency for greater correlation at higher fm~x for stronger magnetic fields. A study of the correlation for C type spectra between fm~x and the quasi-cutoff frequency fq~ on the low-frequency side shows that for bursts of moderate peak flux density (50-500 sfu) fqe is well correlated with fmax; a good fit to the relation fmax--A fqc is found with A--3.4. The possible attenuating mechanisms responsible for the spectral shaping of the cm component are discussed.

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Solar bursts at λ = 2 cm on July 31, 1972

Cited by 10 publications

References 14 publications

Spectral evolution of multiply impulsive solar bursts

Spectral evolution of multiply impulsive solar bursts

A comparison of the optical and microwave emissions of some major solar flares

Spectral distributions of microwave bursts

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