Modulation of the flare activity of the sun with a 160 minute period.
Abstract
The authors subjected to a statistical analysis the complete set of times of beginnings of chromospheric flares of importance B ≥ 1 observed on the sun during 1955 - 1980 (about 16200 flares in total). A high-resolution "power spectrum" of the time series was calculated for a range near the 160.0-min period using the superposed epoch technique and the χ2-criterion. It showed only two significant (⪆99.9% confidence) peaks corresponding to periods 160.0056±2 and 160.0100±2 (min). It is supposed that the 160-min global oscillations of the sun trigger, statistically, occurrences of flares. A peak-to-peak amplitude of this 160-min effect is found to be about 12% with respect to the statistical mean value which would be expected in a random sample. It is noted that the spacing between the frequencies of those two dominant peaks corresponds fairly well to the 11-year period. Nevertheless, some arguments are given in favour of a real (i.e. not arisen merely from 11-year modulation) nature of the duplicate structure of the 160-min period in solar flares. The same seems to be true for Doppler observations of solar oscillations. This, in turn, may lead to interesting conjectures on a possible physical association between 160-min oscillations and the solar 11-year cycle.
- Publication:
-
Izvestiya Ordena Trudovogo Krasnogo Znameni Krymskoj Astrofizicheskoj Observatorii
- Pub Date:
- 1986
- Bibcode:
- 1986IzKry..75...59K
- Keywords:
-
- Solar Cycles;
- Solar Flares;
- Solar Oscillations;
- Chromosphere;
- Power Spectra;
- Statistical Analysis;
- Solar Physics;
- Oscillations:Solar Flares;
- Solar Flares:Oscillations