From chaotic to 1/f processes in solar mcw-bursts
1997; EDP Sciences; Volume: 324; Issue: 2 Linguagem: Inglês
ISSN
1432-0746
AutoresV. B. Ryabov, A. V. Stepanov, P. V. Usik, D. M. Vavriv, В. В. Виноградов, Yu. A. Yurovsky,
Tópico(s)Earthquake Detection and Analysis
ResumoAbstract. Solar bursts with superfine time structure observedat 2.5 and 2.85GHz at the Crimean Astrophysical Observa-tory have been analyzed by means of statistical methods fornonlinear dynamical systems. Finite values of the correlationdimension have not been detected for all the studied events.The presence of a 1/f γ component in many of the processedevents has been found by means of wavelet analysis and max-imum likelihood technique. The model of uncorrelated pulsesis proposed as the one capable of producing a 1/f γ shape ofthe power spectrum. A procedure is developed for extractingthe parameters of pulse sequences from the data, and the mag-nitudes of pulse duration, amplitude, and repetition frequencyare estimated for the solar burst events.Key words: Sun: flares – Sun: radio radiation – chaos – dataanalysis1. IntroductionConsiderable recent attention has been focused on superfinetime structure of solar microwave emission and, in particu-lar, on irregular pulsations with typical time scale of the orderof milliseconds (Slottje 1978; Dennis et al. 1987; Stepanov YBenzAVlahosetal.1983;Zaitsev et al. 1985; Aschwanden 1987; Isliker 1992, Barrow etal. 1994). About ten years ago the hypothesis has been put for-ward that the mechanism responsible for the formation of theirregularbehaviormaybeofdeterministicnature.Inaccordancewith it, the complicated temporal structures in the solar emis-sion detected in many observations have been suggested to bechaoticprocesses,withfinitevalueoftheassociatedcorrelation(fractal) dimension.Preliminary reports (Kurths & Herzel 1987; Kurths & Kar-licky 1989; Isliker 1992) were in favor of such a theory. How-ever, more careful analysis (Isliker & Benz 1994) has revealedthatinalmostallthecasesthedetectedfinitevalueofcorrelationdimension was a spurious effect caused by intrinsic difficulties
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