SW Lac’ın uzun dönemli ışık değişimi

Bu tez calismasi, W UMa turu degen cift yildiz SW Lac’in tutulmalar disinda gosterdigi uzun donemli isik degisiminin kokenine iliskin ayrintili fotometrik ve tayfsal analizleri icermektedir. Fotometrik analizler kapsaminda, sistemin 10 yillik bir zaman araligini kapsayan isik egrilerinin ayrintili analizleri ve 118 yillik zaman araligini kapsayan minimum zamanlari kullanilarak ayrintili donem analizi gerceklestirildi. Tayfsal analizler kapsaminda ise McDonald Gozlemevi’nde elde edilen yuksek cozunurluklu tayflar kullanilarak, S/N oranini arttirmaya yarayan LSD (Least Squares Deconvolution) ve Doppler Goruntuleme Teknigi’ne dayali DoTS kodu yardimiyla sistemin ilk kez yuzey parlaklik dagilimi haritalari elde edildi.   Tayfsal analiz sonuclari ile bilesenler uzerinde, manyetik aktivitenin varligina dogrudan delil sayilan, leke yapilari ortaya cikarilmis oldu. Buna ek olarak isik egrisi ve donem analizlerinden elde edilen sonuclar da sistemdeki manyetik aktivitenin varligi bakimindan tayfsal analizleri destekler niteliktedir. Dolayisiyla bu tez calismasi ile SW Lac’in, tutulmalar disindaki isik degisim dogasi manyetik aktivite kokenli olan, tipik bir W-turu W UMa oldugu net bir sekilde ortaya cikarilmis oldu. Ayrica bu calisma, bu turden degen cift yildizlarin isik degisim dogasina iliskin yapilmis en kapsamli calisma olmasi bakimindan bir ilktir.Abstract   The present thesis includes a detailed photometric and spectral analysis concerning with the origins of long term light variation of the W UMa type contact binary SW Lac, outside the eclipses. Within the context of the photometric analysis, detailed light curve and period analysis were carried out using the light curves spanning 10 years and minima times spanning 118 years, respectively. In point of the spectral analysis, with the help of the signal enhancing technique LSD (Least Squares Deconvolution) and the Doppler imaging code DoTS, the first surface brightness mapping of the system was performed using the high resolution spectra obtained at the McDonald Observatory.   Results from the spectral analysis indicates the spot features, which can be attributed as a direct evidence for the presence of the magnetic activity in the system. In addition, the results obtained from the photometric analysis strengthen the spectral analysis results in point of the existence of the magnetic activity. Thus, with this thesis study, it is revealed that SW Lac is a typical W-subtype W UMa contact binary, which the long-term light variation outside the eclipses is related with the magnetic activity. Besides, this study is the most comprehensive ever, in point of investigating the long-term light variations of such contact systems.