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Öğe A light and period study of SV Camelopardalis(Edp Sciences S A, 2001) Albayrak, B; Demircan, O; Djurasevic, G; Erkapic, S; Ak, HNew BVR light curves and times of minimum light for the short period RS CVn system SV Cam were analysed to derive the physical parameters of the system and the parameters of the third body orbit. The light curves obtained at the TUBITAK National Observatory during two nights in 2000 show considerable asymmetry and night-to-night variations. The analysis of the light curves is made using Djurasevic's inverse problem method. The Roche model with spotted areas on the hotter primary component yields a good fit to observations. The extensive series of published photoelectric minima times indicate that the eclipsing pair orbits around the common mass center of the triple system with a period of 41.32 yr.Öğe Refinement of third body parameters and new photometric results for the early-type multiple system IU Aurigae(E D P Sciences, 2003) Özdemir, S; Mayer, P; Drechsel, H; Demircan, O; Ak, HThe massive eclipsing binary system IU Aurigae is re-analyzed in the context of new photometric observations and an improved treatment of its long-term period changes (O-C diagram) derived from new times of minima. The best-fit of the O-C curve reveals that the third component is orbiting around the system with a period of 293.3 days in a highly eccentric orbit (e = 0.62). A solution of the most recent UBV light curves obtained during 1997/1998 showed a third light contribution of approximate to23% and continuation of the orbital plane precession of IU Aurigae. Since the revised mass of the third component deduced from the analysis of the O-C curve of m(3) = 14.2 M-. would imply a larger fraction of third light than suggested by the value of 23% derived from the light curve analysis, the third body is possibly composed of two components. A q-search test applied to the UBV light curves yields a minimum chi(2) value at q = 0.67 +/- 0.02, which confirms previous photometric and spectroscopic solutions.Öğe The early type contact binary system V 382 Cygni(E D P Sciences, 1999) Degirmenci, ÖL; Sezer, C; Demircan, O; Erdem, A; Özdemir, S; Ak, H; Albayrak, BNew photometric data set of the early type contact binary V382 Cyg have been analyzed with emphasis on determining the photometric mass ratio of the system. The result (q = 0.68) supports the value given by Popper & Hill (1991). A study of the system using new data shows a period increase of about 3.28 s per century, which corresponds to a very large rate similar to 5.0 10(-6) M./yr of mass transfer from the less massive to the more massive component under the conservative mass transfer hypothesis.Öğe UBV photometry of the massive eclipsing binary TT Aur(C S I R O Publishing, 2001) Özdemir, S; Ak, H; Tanriver, M; Gülseçen, H; Gülseçen, S; Saygaç, AT; Budding, EUBV observations of the massive binary system TT Aur were carried out mainly at the Turkish National Observatory (TUG). These observations, together with IUE spectra and times of eclipse minima collected from the literature, were used to study the system parameters. Simultaneous solution of the light curves by the Wilson-Devinney code allows a semi-detached configuration with a slightly larger Roche-lobe filling secondary. This picture is supported by other evidence. The shoulders of the primary minimum suggest some excess absorption, in keeping with circumstellar material in the form of a disk-like structure around the primary component. The deeper primary minimum in the U filter may indicate a hotter region on the secondary-facing hemisphere of the primary. The period variation of the system can also be related to the possible existence of a third component in a circular orbit around the system. An alternative. detached representation is also considered using optimal curve-fitting techniques. We appeal for further observations to help resolve some outstanding issues in this interesting massive binary.
