Solar flare activity is produced by the processes of accumulation and
release of energy in an active region. A complex magnetic structure is
formed over the spots, the reconnection of which leads to the generation
of a flare. The information about the magnetic field can be retrieved
from is polarized microwave radiation, the spectrum of which is correlated
with the flare activity. The polarized emission spectra of the stable
active regions are monotonic (Fig.1), whereas the spectra of
flare-productive active regions reveal sharp dips (Fig.2). In the
framework of study of solar active regions, producing powerful flares
the researchers from the RATAN-600 radio telescope have detected sources
with features in the form of a sharp drop in the intensity of polarized
radiation in various parts of the recorded frequency range (2-16GHz),
sometimes changing the sign of polarization. Modelling of the phenomenon
in the form of a hot coronal loop (Fig.3), located at heights of about
10~Mm (at the height of the transition region of about 22-5Mm) indicates
that the discovered features of polarized light (Fig.4) may be explained
by the presence of a hot region in the solar corona above the active
region. This model and multi-wave observations allow to determine
the magnetic field strength of the hot region (360-450G) and the
product of the relative magnetic field gradient on the thickness of
the loop (0.26-0.63).
Contact - Bogod V.M.
Yasnov L.V., Kaltman T.I., Bogod V.M.
In collaboration with St. Petersburg State University.
Published: AJ, 2010, Vol 87, no. 11, 1-9.