On the Origin and Morphology of Complex Hectometric Type III-like Radio
Emissions Observed by Wind/WAVES
Michael J. Reiner
Cane et al. (1981) identified a class of intense, complex, hectometric-kilometric
type III-like bursts (SA events) that they believed to be produced
by electrons accelerated by blast-wave shocks high in the solar corona.
Verification of this hypothesis, however, was hampered by the lack of radio
observations in the frequency range from ~2 to 20 MHz. Radio receivers
on the Wind spacecraft have recently provided observations in the region
of this frequency gap. In this talk, we review these new observations.
Bougeret et al. (1998) observed one type III-like burst that appeared to
originate from the backbone of a metric type II burst, which are believed
to correspond to coronal shocks. This type III-like burst, which was not
associated with any metric type III or decimetric radio emissions, was
observed to extend through the kilometric wavelength regime. Reiner and
Kaiser (1999) studied the morphological characteristics of intense, complex
type III-like bursts in the frequency range from 1 to 14 MHz and found
distinct differences above and below ~7 MHz, suggesting different origins.
Finally, Reiner et al. (2000) studied a number of complex, hectometric-kilometric
type III-like events that were associated with the simultaneous presence
of decimeter wavelength radio emissions. From a comparison of the shape
and duration of the burst profile at 1 MHz with that at decimetric wavelengths,
they concluded that the complex type III-like bursts were likely generated
by electrons accelerated by the primary flare energy release process.
Cane, H. V. et al., Geophys. Res. Lett., 12, 1285, 1981
Bougeret, J.-L. et al., Geophys. Res. Lett., 25, 2513, 1998
Reiner, M. J. and M. L. Kaiser, Geophys. Res. Lett., 26, 397, 1999
Reiner, M. J. et al., Astrophys. J., 530, xxx, 2000
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