Speaker
Description
We report the first unambiguous observational evidence in the radio range of
the reflection of a coronal shock wave at the boundary of an equatorial coronal hole.
The eruption occurred on 2011 August 11 above active region NOAA 11263 and
was accompanied by an EUV wave, as evinced by AIA/SDO and EUVI/STEREO
observations, and an anomalous reverse-drifting metric type II radio burst,
interpreted as a signature of the reflected shock. By combining EUV images
from AIA and EUVI with radio observations obtained by the Nancay Radioheliograph (NRH),
we show that the reverse-drifting type II radio emission was produced at the
intersection of the shock front, reflected at a coronal hole boundary, with an
intervening low-Alfvén speed region characterised by an open field configuration.
Moreover, we provide a data-driven reconstruction of the
spatio-temporal evolution of the shock-accelerated electron beams produced
by the reflected shock.
