Chromospheric activity nature from cold stars to hot stars

In this study, a research on the nature of "flare", which is one of the most dominant markers of chromospheric activity, known for more than 150 years, is being presented. In the last 5 years, 5 sample systems have been selected with a wide range of activities, ranging from M spectra to F spectra, in order to expand the area of this study in the literature and reach closer results to the true nature of the flares. By applying different types of analyzes such as Fourier and SPOTMODEL to the high time-resolution photometric data, which are obtained from Kepler Mission, of these systems light curve analysis, variation of out-of-eclipses brightness, and so on, after revealing the physical nature of the systems (component temperatures, mass, radius, etc.), the behavior of the flare, which is the subject of this study, is examined. In the high time-resolution data are obtained from the Kepler Mission, of KIC 9641031, KIC 9761199, KIC 11548140, KIC 11231334 and KIC 12004834 systems, flares appearing in the form of instant flashes are calculated, parameters are calculated and the relations between the calculated parameters are examined and modeled. By using these models, we tried to determine the flare behavior in a wide spectral range and attempted to identify them separately under each star. On the other hand, the systems exhibiting cool star spots as an additional product of the study were modeled with cool spot-induced sinusoidal variations, and spot migration periods were calculated. For solar-like pulsating systems, pulsation frequencies were calculated and markers for the coexistence of magnetic activity and throbbing behavior were obtained. In the comprehensiveness of this study, spectral observation of a system was also carried out and radial velocity change, temperature and spectral type of the component were determined by analysis of spectral data. The parameters of three planets are calculated by determining the transit observations of the planets of the system called as a candidate of multiple planetary system in the literature. Keywords: Red Dwarf, Stellar Flare, Stellar Spot, Pulsation, Eclipsing Binary, Exoplanet.