Sharp Changes in the Ordinary Mode Microwave Emission from a Stable Sunspot: Model Analysis

Bezrukov, D.; Ryabov, B. I.; Peterova, N. G.; Topchilo, N. A.

doi:10.2478/v10047-011-0016-7

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…As a matter of fact, the NoRH o-mode images (R polarization for October 1011 and L for March 2016) show brightness depressions at the location of the spot (c.f. Topchilo, Peterova, and Borisevich, 2010;Bezrukov et al, 2011;Ryabov et al, 2015;Bogod et al, 2015). Sunspot-associated omode emission (2nd harmonic) started at at ∼11.9 GHz on October 2011 and ∼ 11.5 GHz on March 2016, which puts the magnetic field intensity at the base of the TR to ∼ 2150 and ∼ 2100 G respectively.…”

Section: Models Of the Radio Emissionmentioning

confidence: 99%

Modeling of the Sunspot-Associated Microwave Emission Using a New Method of DEM Inversion

et al. 2019

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We developed a method to compute the temperature and density structure along the line of sight by inversion of the differential emission measure (DEM), under the assumptions of stratification and hydrostatic equilibrium. We applied this method to the DEM obtained from AIA observations and used the results, together with potential extrapolations of the photosheric magnetic field, to compute the microwave emission of three sunspots, which we compared with observations from the RATAN-600 radio telescope and the Nobeyama Radioheliograph (NoRH). Our DEM based models reproduced very well the observations of the moderate-size spot on October 2011 and within 25% the data of a similar sized spot on March 2016, but predicted too low values for the big spot of April 14, 2016. The latter was better fitted by a constant conductive flux atmospheric model which, however, could not reproduce the peak brightness temperature of 4.7 × 10 6 K and the shape of the source at the NoRH frequency. We propose that these deviations could be due to low intensity non-thermal emission associated to a moving pore and to an opposite polarity light bridge. We also found that the double structure of the big spot at high RATAN-600 frequencies could be interpreted in terms of the variation of the angle between the magnetic field and the line of sight along the sunspot.

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Section: Models Of the Radio Emissionmentioning

confidence: 99%

Modeling of the Sunspot-Associated Microwave Emission Using a New Method of DEM Inversion

et al. 2019

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“…As for the maps taken with resolution of 3′-4′ in the wavelength range 3.2-4.7 cm, there is not any continuous modification of the reduced intensity of the LTRs from one wavelength to another. In addition to the not-completely-restored structures of the LTRs, there is some complicated gyro-resonance contribution to the intensity in cm wavelengths [23]. The bright gyro-resonance emission conceals the depressed emission near the cores of the sunspot-associated microwave sources.…”

Section: Discussionmentioning

confidence: 99%

Low Brightness Temperature in Microwaves at Periphery of Some Solar Active Regions

Ryabov

Bezrukov

Kallunki

2017

Latvian Journal of Physics and Technical Sciences

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The microwave regions with low brightness temperature are found to overlap the regions of the depressed coronal emission and open field lines at the periphery of two solar active regions (ARs). The imaging microwave observations of the Sun with the Nobeyama Radio heliograph at 1.76 cm, the MRO-14 radio telescope of Metsähovi Radio Observatory at 0.8 cm, and the RT-32 of Ventspils International Radio Astronomy Centre in the range 3.2-4.7 cm are used. To reduce the noise in the intensity distribution of the RT-32 maps of the Sun, one wavelet plane of "à trous" wavelet space decomposition is subtracted from each map. To locate the open-field regions, the full-Sun coronal magnetic fields with the potential field source surface (PFSS) model for R SS = 1.8 R ʘ are simulated. We conclude that the revealed LTRs present narrow coronal hole-like regions near two ARs and imply an extra investigation on the plasma outflow.

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“…The list of feasible tasks of solar physics to be solved on the base of spectral polarimetric observations on RT-32 have been discussed earlier . One of such tasks is the analysis of active regions associated with large isolated sunspots (Bezrukov et al 2011). Spectral polarimetric observations of active regions of this kind could now be performed.…”

Section: Discussionmentioning

confidence: 99%

Spectral Polarimetric Observations of the Sun by the VIRAC RT-32 Radio Telescope: First Results

Bezrukov

2013

Open Astronomy

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Sharp Changes in the Ordinary Mode Microwave Emission from a Stable Sunspot: Model Analysis

Cited by 4 publications

References 9 publications

Modeling of the Sunspot-Associated Microwave Emission Using a New Method of DEM Inversion

Modeling of the Sunspot-Associated Microwave Emission Using a New Method of DEM Inversion

Low Brightness Temperature in Microwaves at Periphery of Some Solar Active Regions

Spectral Polarimetric Observations of the Sun by the VIRAC RT-32 Radio Telescope: First Results

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