Modeling of accretion disk-originated absorbtion and/or emission features in the high resolution spectra of the close binary system U SGE

In this thesis, high-resolution spectroscopy of the short-period Algol-type system U Sge which is known to exhibit Hα emission has been done and the emission structures have been analysed. The astrophysical parameters of the system have been obtained by means of analysing the spectral and photometric data. Accordingly, the primary component is a B7-8 spectral type main-sequence star, while the secondary component is a G2 spectral type giant. The cool secondary component has filled its Roche lobe and thus transferring material onto the hot primary component. The affects of both components and the transferring material were detected in the Hα lines. In order to determine these effects, the SHELLSPEC code which uses LTE approximation has been used. The circumstellar structure around U Sge is due to very low density disk, transferring material, a hot spot where the transferring material from the secondary hits and the activity from secondary itself. Moreover, all of these effects on the system show short time scale variations.