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  • Особенности короткопериодических колебаний микроволнового излучения активной области Солнца перед вспышкой.

Article

Особенности короткопериодических колебаний микроволнового излучения активной области Солнца перед вспышкой.

Ядерная физика. 2018. Т. 81. №  3. С. 366-370.
И.А. Бакунина, Абрамов-Максимов В. Е.

Radiation of microwave sources above sunspots at a frequency of 17 GHz gives information on parameters
of solar plasma in the regions of magnetic field B ~ 200 G in the transition region between chromosphere
and corona. Short period (with periods in several minutes) oscillations of microwave emission of solar active
regions (ARs) reflect wave processes in the magnetic flux tubes of the sunspots. We present an analysis of short
period oscillations of microwave emission of AR NOAA 12242 before two flares on December 17, 2014. The
analysis is based on solar radio images, obtained using the Nobeyama Radio Heliograph. The radio maps of
the whole solar disk were synthesized in non-standard mode with a cadence of 10s and 10s averaging. The
spatial resolution of the radio maps is about 10ʹ–15ʺ. We found that about 40–50 min before the M1.5 flare
(01:00 UT) the power of about ten-minute oscillations is increased. At the same day the power of ten-minute
oscillations increased about 60 min before the M8.7 flare (04:42 UT). The observed effect is similar to the
previously detected independently by two authors effect for 3-minute oscillations, namely, for 15–20 min
before radio burst there was increase of the power of 3-minute oscillations. The effect can be interpreted as
a relationship between MHD waves, propagating along the magnetic flux tube of sunspot, and beginning of
the flare.