Abstract. New photometric data set of the early type contact binary V 382 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 ∼ 5.0 10 −6 M /yr of mass transfer from the less massive to the more massive component under the conservative mass transfer hypothesis.

Abstract. New photoelectric observations of the eccentric orbit binary CW Cephei have been carried out in B, V and R colours during the 2000 observing season at TÜBITAK (The Scientific and Technical Research Council of Turkey) National Observatory. The light curves of the system were analyzed with a nonsynchronous rotation approach using the method of Wilson-Devinney in B, V and R bands, simultaneously. Especially, we used the R band to check for a third light in the solution as distinct from previous studies. But, the third light contribution in the light curves comes out to be almost negligible. In this study, the values of the longitude of periastron (ω) of the system's orbit found in the solutions of the light curves and radial velocity curves were collected and the variation of ω with time was investigated. A new value of the apsidal motion velocity has been obtained asω=0.0582 ± 0.0011 (deg/cycle), corresponding to an apsidal period U=46 ± 1 yr.

Photoelectric observations of the WR binary CQ Cephei (WN6S09) are presented. The depths of the eclipses in the light curves are best represented by an inclination of the orbit z = (68O.8 f 0.6) and the width of the very asymmetric eclipse curves can be represented by only an overcontact configuration (01 = Rz = 3.65 f 0.05, and f = 27% Here, we report the new photometric data, present the results of a new analysis of the photometric data, and discuss the nature of the system revealed by the new analysis. 2. ObservationsPhotoelectric UBV observations were obtained in 1995 and 1996 in 7 nights with the 30 cm Maksutov telescope, and in 16 nights with the 30 cm Cassegrain telescope, both at the Ankara University Observatory. The photometers used are the standard SSP-5 in the Maksutov, and SSP-5A in the Cassegrain telescopes. BD +56"2815 and BD

No abstract

Abstract. The 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 ≈23% 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 χ 2 value at q = 0.67 ± 0.02, which confirms previous photometric and spectroscopic solutions.