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T. I. Kaltman, V. M. Bogod St. Petersburg branch of Special Astrophysical Observatory, Russia

On the Structure of Magnetic Field and Radioemission of Sunspot-related Source in Solar Active Region. A. G. Stupishin, L. V. Yasnov Radio Physics Research Institute, St. Petersburg University, Russia. T. I. Kaltman, V. M. Bogod

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T. I. Kaltman, V. M. Bogod St. Petersburg branch of Special Astrophysical Observatory, Russia

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  1. On the Structure of Magnetic Field and Radioemission of Sunspot-related Source in Solar Active Region A. G. Stupishin, L. V. Yasnov Radio Physics Research Institute,St. PetersburgUniversity, Russia T. I. Kaltman, V. M. Bogod St. Petersburg branch ofSpecial Astrophysical Observatory, Russia

  2. Goal: To develop methods of physical condition diagnostics in the transition region and the lower corona on the base of reconstructed magnetic field and observations of radio emission on RATAN-600 radiotelescope. To estimate physical conditions in particular active regions with simple configuration AR 10933, AR 10935. RATAN-600 characteristics: frequency range: 0.75 … 18.2 GHz 112 frequencies in R and L polarization max. angular resolution: 2 arcsec brightness temperature limit: 5∙10-5 K

  3. AR 10933 6 GHz RATAN-600 scans 12 GHz MDI 14 GHz Source separation 16 GHz

  4. AR 10933: RATAN scans compare with: UV 195Å (EIT) Lines of reconstructed Magnetic Field Photosphere Magnetic Field (MDI)

  5. Magnetic field reconstruction: • Source data of 3D photospheric magnetic field – Hinode/SOT instrument Hinode is a Japanese mission developed and launched by ISAS/JAXA, with NAOJ as domestic partner and NASA and STFC (UK) as international partners. It is operated by these agencies in co-operation with ESA and NSC (Norway). 180-degree ambigity was resolved using minimal temperature method (Metcalf, T.R.: 1994, Solar Phys. 155, 235) with optimization suggested at (Leka, K.D., Barnes, G., Crouch, A.D., Metcalf, T.R., Gary, G. A., Jing, J., Liu, Y.: 2009, Solar Phys. 260, 83) (inhomogeneous initial temperature). Potential magnetic field was reconstructed according (Nakagawa, Y., Raadu, M.A.: 1972, Solar Phys. 25, 127; Allissandrakis, C.E.: 1981, Astron. Astrophys.100, 197) (concerning Bz component is not perpendicular to photosphere). On the base of reconstructed potential field (as initial condition) and full 3D magnetic field on photosphere (as boundary condition) non-linear force-free field (NLFFF) was calculated by Landweber iteration algorithm (Wiegelmann, T.: 2004, Solar Phys. 219, 87).

  6. AR 10933 Gyroresonance levels at 3 cm (10 GHz), 3rd harmonic: 3D view at 1.25 Mm Reconstructed magnetic field – 3D view at 1.75 Mm

  7. Optical thickness depends on: • emission mode (o-, x-mode), • wavelength, • angle, • magnetic field, • electron density, • electron temperature. Emission transition equation solution:

  8. Model parameters adaptation procedure Effective heights of optical thickness = 1 Temperature distribution: Modify distribution Observations vs. model Calculated maps of brightness temperature Obtain calculated scans by convolution with the telescope beam

  9. AR 10933 Model electron temperature and density Spectra: observations vs. model Left polarization Right polarization Observation Model

  10. AR 10933 Observations vs. model: scans Observation Model Difference Right Left

  11. Effective heights of the free-free emission Spectrum by RATAN-600, gyroresonance (gr) and free-free (ff) emission mechanisms AR 10935

  12. Conclusions Method of active region physical condition diagnostic, based on • multiwave observation of polarized emission in centimetric waverange on RATAN-600, • Magnetic field extrapolation, • Calculation of radioemission allows • To estimate the electron density distribution at different height in different parts of active region, • To estimate the relative contribution of cyclotron and free-free emission at different wavelengths, • To estimate the contribution of various cyclotron emission harmonics, • To correct active region structural component sizes estimations. Analyses based on AR 10933 and 10935 shows that reconstructed magnetic field corresponds to observed sizes of radiosources at high frequencies, but at low frequencies observed sizes is smaller that modeled ones. It can be solved by introduction of different density and temperature distribution over and outside the spot. Another possible reason is not full adequacy of magnetic field reconstruction. Reconstructed magnetic field of simple one-spot active region can be used to modeling of active region structure and matches well with microwave observations in general. Comparison of observed and calculated radioemission give us the follow estimation of physical condition in analyzed active regions: • Low corona begins at the heights 2.0 … 2.3 Mm, • Corona temperature is 2.5 MK at low heights and, possibly, rises to 3.0 MK higher, • Electron density in low corona is about 1.5 … 1.8∙109 cm-3.

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