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Salakhutdinova, I. I.

doi:10.1023/a:1016555207872

Cited by 16 publications

(2 citation statements)

References 9 publications

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“…Fractal processes have also been associated with the Sun, including its global activity (Salakhutdinova 1998), radio bursts (Veronig, Messerotti & Hanslmeier 2000) and large‐scale magnetic field (Burlaga, Wang & Ness 2003). The small‐scale magnetic structure too appears to possess many fractal features (Abramenko 1999; Janßen, Vögler & Kneer 2003; Stenflo & Holzreuter 2003).…”

Section: Astronomical Fractals and Fractal Sourcesmentioning

confidence: 99%

Gravitational microlensing of fractal sources

Lewis

2004

Monthly Notices of the Royal Astronomical Society

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Gravitational microlensing has proven to be a powerful tool in the study of quasars, providing some of the strongest limits on the scales of structure in the central engine. Typically, sources are considered to be smoothly varying on some particular scale; such simple sources result in recognizable time-scales in microlensing light curves from which the size of the source can be determined. Various emission processes, however, result in sources with a fractal appearance, possessing structure on a range of scales. Here, the gravitational microlensing of such fractal sources at the heart of quasars is considered. It is shown that the resulting light curves reflect the fractal nature of the sources, possessing pronounced structure at various scales, markedly different to the case with the random distribution of emission clouds that are typically considered. Hence, the determination of a characteristic scale of variability in a microlensing light curve may not necessarily reveal the size of the individual emission clouds, the key value that is required to determine the physical state of the emission region, rather it may correspond to a particular hierarchy in a fractal structure. Current X-ray satellites can detect such fractal structure via the monitoring of gravitationally lensed quasars during a microlensing event, providing a test of high-energy emission processes in quasars.

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Section: Astronomical Fractals and Fractal Sourcesmentioning

confidence: 99%

Gravitational microlensing of fractal sources

Lewis

2004

Monthly Notices of the Royal Astronomical Society

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“…The technique of fractal analysis of experimental data includes a procedural apparatus, from estimating the fractal dimensions of the object's geometry, taking into account their relation to the Hurst index and spectral index [6][7][8][9][10][11][12], to the techniques used to calculate the multi-fractal parameters of the physical fields. These techniques include the use of structure * E-mail: golovko@iszf.irk.ru functions [1,13], Detrended Fluctuation Analysis (DFA), which involves the development of a onedimensional random-walk model [14], the Wavelet Transform Modulus Maxima (WTMM) technique, which is based on the wavelet transform [15], the use of moments of the partitioning function, and the micro-canonical technique of multi-fractal segmentation [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Fractal properties of active regions

Golovko

Salakhutdinova

2012

Astron. Rep.

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The dynamics of active regions have been investigated using multi-fractal analysis methods, based on magnetograms of the full solar disk in the 630.2 nm line obtained with the SOLIS vector spectromagnetograph of Kitt Peak Observatory (USA) during The applied method of multi-fractal segmentation reveals the appearance of new magnetic fluxes on the Sun disk. A comparison of these fluxes with flare activity shows that the flares are generated in areas of interaction of emerging fluxes with existing structures.

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The variations of the scaling parameters of the structure functions in solar active regions at the pre-flare stage

Salakhutdinova

Golovko

2004

Sol Phys

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A series of subflares in active region NOAA 9077 (July 2000) and in the activity complex NOAA 0039 + NOAA 0050 were investigated. The structure functions and their characteristics for sets of images of active regions in the hydrogen-alpha line (Hα-line) were calculated. The ranges of the spatial scales of different scaling behavior of the structure functions were revealed. The existence of intermittent turbulence (multi-fractal structure) in active regions of the chromosphere is shown. Peculiarities of the scaling parameters variations of the structure functions at pre-flare stage are investigated. It was found that on average 20 min before a subflare onset considerable deviation of these variations from the mean occurs, which may be of importance for predictions. It was discovered that maximum variations of scaling parameters with an accuracy to 15 min (on average), in a number of cases coincide with variations of the elongated chromospheric structures in an active-region area. We used H α filtergrams obtained with the chromospheric telescope of the Baikal observatory operated by ISTP SD RAS. The telescope is coupled with a Halle birefringent filter with a 0.05 nm bandpass, and a Princeton Instruments 2048 × 2048 pixel CCD camera with 16-bit amplitude resolution.

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Untitled

Cited by 16 publications

References 9 publications

Gravitational microlensing of fractal sources

Gravitational microlensing of fractal sources

Fractal properties of active regions

The variations of the scaling parameters of the structure functions in solar active regions at the pre-flare stage

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