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Reconstruction of the Atmosphere of the Solar Corona
over a Spot from Current Data

Russian version

    First temperature measurements over active regions have been obtained based on an automatic iterative method applied to the data observed at RATAN-600. The detection is based on observations of the polarized radio emission at the RATAN-600 radio telescope and radio emission calculations in the magnetic field extrapolated to the Solar corona (according to the photospheric magnetogram SDO / HMI data).
    To evaluate electronic temperature, we developed an iterative method based on calculation of cyclotron radio emission in the range of 2-18 GHz, on convolution of radio maps with the diagram of the telescope and comparison with the observed data at several tens of wavelengths. The method has been applied for several active regions with bright single spot sources with a high degree of polarization at high frequencies (which indicates the cyclotron radiation without significant heat braking contribution).
    We have received temperature increase in the transition region and lower corona being consistent, generally, with the adopted Selhorst model based on individual characteristics of active regions. The results are in a good agreement with direct measurements of the magnetic field at the base of the corona from radio observations (on the assumption of cyclotron radiation at the 2nd and 3rd harmonic gyro frequency) and allow us to specify the height estimate for these measurements.
Kaltman T.I., Bogod V.M. (SAO RAS) in collaboration with Stupishin A.G., Yasnov L.V. (SPbU)
Stupishin A., Bogod V., Kaltman T., Yasnov L., Modeling of solar atmosphere parameters above the active region using RATAN-600 radiotelescope observation, Programme and abstracts of CESRA 2016: Solar Radio Physics from the Chromosphere to Near Earth 13-17 June 2016, Orleans (France), electronic issue, p. 100

Contact - Kaltman T.

Fig.1. Temperature increase over the spots in the transition region and lower corona: to active regions 11899, 11312, and 11289 (the colored line), the Selhorst model (the black line for the undisturbed Sun, the dashed for the active region)

Fig.2. Results of applying the method to the active region 11312: left - the scans from RATAN-600 overlaid on the HMI magnetogram, center - the model and observed spectra, right - the temperature increase with the magnetic field estimates measured with the radio astronomical method