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Bastian, Tim
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Institute: National Radio Astronomy Observatory
First Coauthor: Monique Pick
Institute: Alain Kerdraon
Second Coauthor: Dalmiro Maia
Institute: Angelos Vourlidas
Subject Area: The Sun
Waveband: Radio
Technique: Imaging (Direct)
Presentation:
Title: The Coronal Mass Ejection of 1998 April 20:
Direct Imaging at Radio Wavelengths
Abstract: We observed the fast coronal mass ejection of 1998 April 20
with the radioheliograph at Nancay, France, between 164-432
MHz. Spectroscopic data were obtained between 40-800 MHz by
the
spectrometer at Tremsdorf, Germany, and between 20 kHz and
14 MHz with the WAVES instrument on board the WIND
spacecraft. Energetic particle data were obtained from the
WIND 3D Plasma and Energetic Particle experiment. The CME
was observed in white light by the LASCO
coronagraphs on board the SOHO spacecraft.
For the first time, the expanding CME loops are imaged
directly at
radio wavelengths. We show that the radio-emitting CME
loops are the
result of nonthermal synchrotron emission from electrons
with
energies of
MeV interacting with magnetic
fields of
to a few Gauss. They appear nearly
simultaneously with
the onset of an associated type II radio burst,
shock-accelerated type
III radio bursts, and the initiation of a solar energetic
particle
event. We suggest possible sources of the energetic
electrons
responsible for this ``radio CME'' and point out diagnostic
uses for synchrotron emission from CME loops.
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Cool Stars 12
2001-07-23