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Cosmic Research

, Volume 57, Issue 1, pp 1–9 | Cite as

On Detecting the Fourth Gyrofrequency Harmonic in Microwave Emission Spectra above Sunspots

  • T. I. KaltmanEmail author
  • V. M. Bogod
Article
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Abstract

Spectral polarization observations of radio sources above sunspots are regularly carried out with the RATAN-600 radio telescope (RATAN is a Russian acronym for the Radio Astronomical Telescope of the Academy of Sciences). The in-depth studies of the spectra reveal new effects. In this paper, we analyze the manifestation of radio emission of the fourth gyrofrequency harmonic in microwave spectra obtained with 1-percent frequency resolution in a range of 3–18 GHz. Registration of the extraordinary mode in the short-wavelength range of the spectrum is compared to the model calculations of the second-to-fifth gyrofrequency harmonics against a background of the thermal bremsstrahlung emission of flocculi, surrounding the spot structure of an active region. The brightening of the extraordinary mode in the short-wavelength spectral range and the kinks in the intensity spectra of emission are analyzed. The interpretation of the RATAN-600 observational data with probable diagnostics of the emission of the fourth gyrofrequency harmonic is considered as examples.

Notes

ACKNOWLEDGMENTS

The study was performed according to the Government Contract no. АААА-А17-117011810013-4 and supported in part by the Russian Foundation for Basic Research (project no. 18-02-00045) and Program 28 of the Presidium of the Russian Academy of Sciences (Cosmos: Studies of Fundamental Processes and Their Interrelations, project 1D).

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© Pleiades Publishing, Ltd. 2019

Authors and Affiliations

  1. 1.Special Astrophysical Observatory, St. Petersburg Branch, Russian Academy of SciencesSt. PetersburgRussia
  2. 2.ITMO UniversitySt. PetersburgRussia

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