Present state of the study of 160-minutes solar oscillation
โ Scribed by A. B. Severny; V. A. Kotov; T. T. Tsap
- Book ID
- 104643779
- Publisher
- Springer
- Year
- 1981
- Tongue
- English
- Weight
- 330 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0038-0938
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โฆ Synopsis
Global oscillation of the Sun with a period of 160 rain were first discovered in 1974 and since observed in Crimea during the last 6 years; they were confirmed, in 1976-1979, by Doppler measurements at Stanford (Scherrer et al., 1980) and quite recently by observations of Fossat and Grec at the south geographic pole. The average amplitude of the oscillation is about 0.5 m s -1. The phase shows remarkable stability at the period 160.010 min and good agreement between different sites on the Earth; therefore, this oscillation should now be recognized as definitely of solar origin. It is probably accompanied by synchronous fluctuations in the IR brightness and radio-emission of the Sun, and exhibits a dependence of the amplitude on the phase of solar rotation (with a peak of power at 27.2 days).
In agreement with results of the Birmingham group and the South Pole observation we also find evidence in favour of a discrete spectrum within the 5 min global oscillations of the Sun, with the average splitting of about 69.5 ixHz in frequency.
Strict gas-dynamical equations being solved in the adiabatic approximation for a polytropic sphere n = 3 display the pattern of radial oscillations with wave packets separated by 120 m time-intervals filled with high frequency (and split by 117 txHz) oscillations implying a similarity with the observed pattern.
๐ SIMILAR VOLUMES
The 5-min oscillations in the photospheric velocity fields have been studied in detail from measurements on 14 absorption lines from three time sequences of spectrograms of high quality. The lines cover a range of heights in the solar atmosphere from log z = + 0.2 to --1.2. Regions oscillating coher