Confirmation of the 25.5-day fundamental period of the Sun using the north-south asymmetry of the flare index |
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| Authors: | Atila Özgüç Tamer Ataç |
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| Institution: | (1) Kandilli Observatory, Bogaziçi University, Çengelköy, 81220 Istanbul, Turkey |
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| Abstract: | Short-term periodicities of solar activity were studied. To perform the study, a north-south asymmetry time series was constructed by using the northern and the southern hemisphere flare index values for solar cycle 22. The statistical significance of this time series was calculated. It indicates that in most of cases the asymmetry is highly significant during cycle 22. Power spectral analysis of this time series reveals a periodicity around 25.5 days, which was announced before as a fundamental period of solar activity (Bai and Sturrock, 1991). To investigate the time agreement between the two hemispheres, the phase distribution was studied and a phase shift of about 0.5 was found. An activity trend from the north to the south was found. |
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