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The recently-discovered eclipsing double-lined spectroscopic binary V505 Persei (SAO 23229) consists of two nearly identical F5 main sequence stars in a 4.2 day orbit. We have obtained both spectroscopic and photometric observations of the binary that densely sample the complete cycle of radial velocity and light variations. These observations have been used to determine the elements of the orbit, to determine individual masses of the stars in the system to a precision of better than 1%, and to estimate an age for the system. The derived properties agree well with current stellar structure models and provide fundamental data for tests of stellar evolution theory.

In order to get a satisfactory understanding of the periodic variation of the orbital period in the binary system HS Herculis, the study of this problem is resumed. Using recently observed primary and secondary minima, it is evident that after 1955 ( E > -2000) the corresponding 0 -C diagram reflects the effect of apsidal motion. Any assumption on the presence of a third body is rejected, at least as long as the current aspect of the 0 -C diagram is concerned. For the interpretation of the sinusoidal period variation of the semi-detached system SW Cygni, 130 primary minima were compiled from the literature. Though it is considered as very likely that this variation of the period is primarily caused by apsidal motion, the hypothesis of a third body is analysed too. Further precise photometric and spectroscopic observations are recommended.

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