Coronal magnetic field in the transition region from the chromosphere to corona above sunspots on microwave observations: possibilities of researches and problems
Spectral and polarization observations of the Sun in radio waves, as we know, give the possibility to investigate the coronal magnetic field (CMF) in a wide interval of heights from the photosphere level to distances ~ 100 thousand km, now – in detail ~ 100 km. Using the theory of solar radio emission, some methods for studying both strong fields (2–3) KGs (transition region from the chromosphere to corona), and weak (10–100) Gs (plage brightnings, “halo” like sources, prominences) are developed. The results of investigation of the chromosphere-corona transition region above the main sunspot of NOAA 11140 (January, 2011) are given. It turned out that results of observations over the entire range of microwave radiation (2–13) cm can’t be explained within a unified model of the CMF and there is need to use different models for the bottom and top corona. For an adequate interpretation of the observations we proposed to combine a solenoid model (short wave) with a dipole one (long wave). Some calculations are made and the area of applicability of both models is defined.
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