Detection of a cyclotron line in the radio spectrum of a solar active region and its interpretation |
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| Authors: | V M Bogod V I Garaimov V V Zheleznyakov E Ya Zlotnik |
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| Institution: | (1) Special Astrophysical Observatory, St. Petersburg Branch, St. Petersburg, Russia;(2) Institute of Applied Physics, Nizhnii Novgorod, Russia |
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| Abstract: | Observations of the active region AR 7962 obtained at 2–32 cm on the RATAN-600 radio telescope on May 10–12, 1996, are presented. The high-resolution measurements detected a narrow feature near 8.5 cm against the background of the smooth spectrum of the local source associated with sunspots. This narrow-band emission is identified with a bright, pointlike, high-frequency source at 1.7 cm recorded on maps made using the Nobeyama radio telescope. The characteristics of the observed line (lifetime 3 days, brightness temperature of the order of several million Kelvin, relative width of about 10%) suggest that it can be explained as thermal cyclotron radiation at the third harmonic of the electron gyrofrequency from a compact source containing a dense, hot plasma; the corresponding higher frequency emission could be due to thermal Bremsstrahlung. Analysis of the RATAN-600 and Nobeyama data can be used to probe the magnetic field, kinetic temperature, and electron density in the radiation source in the corona. |
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