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Multi-wavelength study of white-light flares
Mravcová, Lucia ; Švanda, Michal (advisor) ; Zemanová, Alena (referee)
Solar flares are common and strong demonstrations of solar activity. They are observable throughout the whole electromagnetic spectrum. If they show a broadband emission in the visible continuum, then we speak of white-light flares. The origin of white-light flares is not fully understood. We detected 24 white-light flares in SDO/HMI data and analyzed them using SDO/AIA wavelength bands at 1 700 ̊A and 304 ̊A and GONG Hα observations. According to our work, the emission in the 1 700 ̊A band is similar to the white-light emission but usually starts sooner. The positions of intensity enhancements in the 1 700 ̊A band are similar to the positions of the white-light flares and are connected by ribbons visible in the 304 ̊A band and in the Hα line. Then we studied the decay time of white-light flares and found that for most of the white-light flare points the typical decay time ranges in 2 - 3 min. 1
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Flare stars
Kára, Jan ; Wolf, Marek (advisor) ; Švanda, Michal (referee)
The works deals with the study of the flare stars, which is a group of stars for which sudden brightening can be observed. The work focuses on a star GJ 3236, which is a low-mass eclipsing binary and on which numerous flares have been observed. For the analysis of this system spectroscopic and photometric data were used, which were obtained at various observatories. Parameters of the binary system have been determined by analysing spectroscopic and photometric data with the program PHOEBE. A total of 241 flares have been detected in the photometric data and for 190 flares, which light curves were not affected by eclipses, released energies were estimated. The set of flares was used for the study of stellar activity of the binary. The energy distribution of observed flares is similar to the flares observed on other flare stars and also on the Sun. This suggests, that the flare mechanism is the same for these stars.
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Solar Flares from Optical to X-ray Emission
Nejedlý, Jaroslav ; Kašparová, Jana (advisor) ; Řípa, Jakub (referee)
Solar flare is a phenomenon during which a large amount of energy is released in various forms. Part of this energy is released in form of different electromagnetic radiation. By analysing hard X-ray spectra of such emission it is possible to derive various parameters of a flare. Thanks to accurate images of solar atmosphere in comparatively high resolution, it is possible to analyse spatial structure of solar flares. By combining data from RHESSI, SDO, GOES, and ground-based observatories, it is feasible to gain an overview of various aspects of solar flares. Combination of multiple different observations of same event will allow us to compare obtained results. The result of this thesis is an analysis of spectra and spatial structures of two selected flares and derivation of their parameters. 1
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Multi-wavelength study of white-light flares
Mravcová, Lucia ; Švanda, Michal (advisor) ; Zemanová, Alena (referee)
Solar flares are common and strong demonstrations of solar activity. They are observable throughout the whole electromagnetic spectrum. If they show a broadband emission in the visible continuum, then we speak of white-light flares. The origin of white-light flares is not fully understood. We detected 24 white-light flares in SDO/HMI data and analyzed them using SDO/AIA wavelength bands at 1 700 ̊A and 304 ̊A and GONG Hα observations. According to our work, the emission in the 1 700 ̊A band is similar to the white-light emission but usually starts sooner. The positions of intensity enhancements in the 1 700 ̊A band are similar to the positions of the white-light flares and are connected by ribbons visible in the 304 ̊A band and in the Hα line. Then we studied the decay time of white-light flares and found that for most of the white-light flare points the typical decay time ranges in 2 - 3 min. 1
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Flare stars
Kára, Jan ; Wolf, Marek (advisor) ; Švanda, Michal (referee)
The works deals with the study of the flare stars, which is a group of stars for which sudden brightening can be observed. The work focuses on a star GJ 3236, which is a low-mass eclipsing binary and on which numerous flares have been observed. For the analysis of this system spectroscopic and photometric data were used, which were obtained at various observatories. Parameters of the binary system have been determined by analysing spectroscopic and photometric data with the program PHOEBE. A total of 241 flares have been detected in the photometric data and for 190 flares, which light curves were not affected by eclipses, released energies were estimated. The set of flares was used for the study of stellar activity of the binary. The energy distribution of observed flares is similar to the flares observed on other flare stars and also on the Sun. This suggests, that the flare mechanism is the same for these stars.
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Study of white-light flares
Mravcová, Lucia ; Švanda, Michal (advisor) ; Heinzel, Petr (referee)
Solar flares are a relatively common and strong demonstration of the solar ac- tivity and are observable throughout the whole electromagnetic spectrum. Some- times, solar flares are also accompanied with an emission in white-light contin- uum, then we speak of white-light flares. The origin of white-light flares is not entirely understood up to this day. The detection of white-light flares can be difficult, therefore we developed a program for automatic detection of white-light flares in SDO/HMI observations. After that, we studied properties of the detected white-light flares. Our work implies that there are two types of white-light flares depending on an X-ray flux of a solar flare. The difference between these two groups can be caused by a different behaviour of the magnetic field in the neigh- bourhood of the detected white-light flares. Our discovery could help in a better understanding of the origin of white-light flares. 1
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