, Volume 155, Issue 2, pp 373-390

Fine structure in a metric type IV burst: Multi-site spectrographic, polarimetric, and heliographic observations

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The spectral fine structure of solar radio continua is thought to reveal wave-particle and wave-wave interactions in magnetic traps in the solar corona. We present observations of spectra, polarization, and spatial characteristics of combined emission/extinction features (‘zebra patterns’) during a decimetric/metric type IV event on 5 June, 1990. Very high modulation depths are observed. The size and location of the sources during emission and extinction are determined for the first time. Two remarkable features are found: (1) The sources of emission stripes have finite size, up to nearly 2′; during extinction stripes the brightness is reduced across the whole extent of the unperturbed continuum, which is slightly larger than 2′. (2) During emission stripes the sources drift over distances up to several × 104 km, with apparent velocities up to 105 km s−1. The observed features are briefly discussed with respect to interpretations based on wave-particle interactions and on the scattering of electromagnetic waves.