Yazar "Kaya, N. O." seçeneğine göre listele
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Öğe Chromospheric activity behavior of an eclipsing binary system KOI 68AB(Wiley-V C H Verlag Gmbh, 2019) Kaya, N. O.; Dal, H. A.We present the results obtained from KOI 68AB's light variation, which exhibits a sinusoidal light variation due to the stellar spots. Two active regions longitudinally separated by about 180 degrees between the latitudes of +70 degrees and +110 degrees were found. A total of 313 flares were determined, and flare parameters were calculated. the One Phase Exponential Association model was derived using these parameters. the energy saturation parameter Plateau value was found to be 1.219 +/- 0.088 s, and its time scale parameter half-life value was found to be 1,190 s. the flare number per hour, known as N-1 frequency, was found to be 0.02406 h(-1), while the flare-equivalent duration emitted per hour, known as N-2, was found to be 0.000008. Considering new spectral observations, the target seems to be an eclipsing binary system. Because of this, the light curve is analyzed under an assumption that the target is an eclipsing binary. in these analyses, the sum of the fractional radii is found to be 0.1908, and the fractional radii ratio is 1.8973.Öğe Semi-Stable Active Region Around the Co-Rotation Latitude of Low-Mass Close Binary KIC 7671594(Wiley-VCH Verlag GmbH, 2024) Kaya, N. O.; Dal, H. A.We present the new findings from the light variation of KIC 7671594. We have analyzed the light curve of the system, which is likely a low-mass eclipsing close binary. We have detected a spotted active region migration on the active component. This spotted active region on the stellar surface appears to be stable during the first 2.70years, but it exhibits rapid migration during the last 0.85years of the observing season. The OPEA model was derived using 1128 flares and their corresponding parameters. In the model, the Plateau value was found to be 2.46703 +/- 0.25234s, and the half-life was calculated as 7332.28s. The flare N-1 frequency was determined to be 0.03719 h(-1), while N-2 was found to be 0.00028. We have concluded that KIC 7671594 is likely a low-mass eclipsing binary system with a main sequence component that possesses an active region covered by some cool spots around its co-rotation latitude.Öğe Some findings from the longitudinal migration of starspots(Cambridge Univ Press, 2024) Kaya, N. O.; Dal, H. A.We present results regarding the longitudinal migrations of cool stellar spots that exhibit remarkable oscillations and explore their possible causes. We conducted analyses using high-quality data from nine target systems of various spectral types, spanning from F to M, which were observed by the Kepler Satellite. The systems in which the behaviour of the spots was examined are as follows: KIC 4357272, KIC 6025466, KIC 6058875, KIC 6962018, KIC 7798259, KIC 9210828, KIC 11706658, KIC 12599700, and KIC 8669092. Basic stellar parameters were calculated from light curve analysis using the PHOEBE V.0.32 software, and light curves were modelled to obtain sinusoidal variations occurring out-of-eclipses phases, induced by rotational modulation. Subsequently, we calculated the minimum times of the obtained sinusoidal variations using the Fourier transform. The distributions of theta(min) corresponding to these minimum times over time were computed using linear fits to determine the longitudinal migrations of the spotted areas. We then compared the longitudinal migration periods with the stellar parameters found in the literature. In addition, we also found a secondary variation in the spot migrations apart from the linear models. Our results revealed that the longitudinal migration periods vary in relation to the B-V colour index of the stars.
