Radio observations and interplanetary particle measurements have
shown that even in the absence of conspicuous violent processes in the low
atmosphere (such as Hα flares) electrons are accelerated in the corona, most
likely at higher altitudes than during flares (≥0.5 R above the
photosphere). The paper presents direct evidence on the acceleration sites from
a case study of radio, visible light and soft X-ray observations: electrons are
repeatedly accelerated in a large-scale coronal structure which is identified
with a streamer in coronographic observations. Energy is simultaneously
released in an active region near the base of the structure and at a height of
∼1 R , over several hours before the large-scale structure erupts. Energy
input is observed in at least two emerging active regions underneath the
streamer. The coronal configuration is three-dimensional, overlying a whole
quadrant of the Sun. It is argued that the observations trace multiple sites of
energy release presumably in current sheets embedded within the streamer, in
agreement with scenarios developed for the acceleration of electrons seen in
the corona and at 1 AU, and for the evolution of large-scale coronal structures
towards eruption
