On quasi-periodic components with periods from 30 to 60 min of amplitude fluctuations of X-band solar radio emission
✍ Scribed by M. M. Kobrin; A. I. Korshunov
- Book ID
- 104657992
- Publisher
- Springer
- Year
- 1972
- Tongue
- English
- Weight
- 194 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0038-0938
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✦ Synopsis
Special experiments have been performed to investigate the fluctuations of the intensity difference of the solar radio emission at two close frequencies. The autocorrelation functions and their spectra are obtained. The latter shows the presence of quasi-periodical components with periods of about 50 min in the solar radio emission. The possibility of explaining the observed quasi-periodical components by the supergranulation oscillations and the solar self-oscillations is considered.
A study of solar radio emission fluctuations has shown a certain number of quasiperiodic components with periods within 100 s to 20 rain (Durasova et aI., 1971). If the observation time was long enough components with longer periods (up to 60 rain) were sometimes detected. Their solar origin, however, was doubtful since they might have been caused by large-scale inhomogeneities of the atmosphere (Durasova et al., 1970). Therefore in 1969 special experiments were carried out on the basis of which the presence of the quasi-periodical components of about 30 and 60 rain period in the spectrum of solar radio emission fluctuations was reported (Kobrin et al., 1970).
Comparing two signals received from the Sun at close frequencies a quasi-zero method was performed (Belov et al., 1969) Such reception enabled us essentially to decrease the influence of the receiver gain fluctuations and the errors in guiding the Sun (since the sharpness of the resulting diagram decreases), and what was most significant, to drastically reduce the effects of the radio wave propagation in the Earth's atmosphere.
A radio telescope with a 4.5 m (in diameter) parabolic reflector is used for the observation. It is mounted on an equatorial installation. For one-channel reception the sensitivity of the receiver is 0.2 K. The integration time is 32~. The frequencies are 9870 MHz and 9670 MHz (direct and mirror channel of superheterodyne). The average temperature of the antenna directed to the Sun is T o ~ 7000 K for one channel and T 1 -T 2 ~ 200 K for both.
For treatment we have selected the records made on the 31st of July 1969 from 6h25 m to 1 l n30 nl, on the 18th of August 1969 from 4h30 m to 14hl 5 m and on the 19th of August 1969 from 4h10 m to 8~45 m UT. The observations were carried out at a cloudless sky and when the height of the Sun was not less than 9 ~ above the horizon. The test records were made when the antenna was directed to the sky to check up the feasible contribution of instability of the apparature into the spectrum of the examined fluctuations. The records obtained were treated in the computer 'BESM-4'. After the pre-