Publication: On Short-Term Periodicity Of The Solar Radius Measurements
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Springer, Van Godewijckstraat 30, 3311 Gz Dordrecht, Netherlands
The aim of the present study is to investigate the short-term periodicity in the solar radius measurements and to compare with the short periods in sunspot numbers, sunspot areas and flare index data. The spectral analysis of data sets covering a time interval from 26 February 2000 to 26 October 2007 during Solar Cycle 23 were made by using the Date Compensated Discrete Fourier Transform (DCDFT). The power spectrum of solar radius data corrected for the seeing effect gives an evident peak at 25.7 days with the amplitude of 0.034 arcsec, which is slightly different from the peaks of 26.2 and 26.7 days produced by sunspot numbers and sunspot areas data, respectively. Besides, the main peak of 25.7 days detected in the power spectrum of solar radius data is in agreement with the period of 25.5 days, suggested to be the fundamental period of the Sun by Bai and Sturrock (in Nature 350, 141, 1991).
solar radius, sunspot activity, flare index, short periodicities, calern-observatory astrolabe, diameter measurements, ccd astrolabe, flare index, time-series, spectral-analysis, disk sextant, solar-cycle-23, variability, constancy, güneş yarıçapı, güneş lekesi aktivitesi, parlama indeks, calern-gözlemevi usturlap, çap ölçümleri, ccd usturlap, parlama indeks, Zaman serisi, spektral analiz, Disk sekstant, Güneş döngüsü-23, değişkenlik, sabitlik