AbstractWe present the precise multicolour photometry of the eclipsing variable EQ Boo (P = 5d.43, V = 8m.8), which is component “A” of the visual double star ADS 9422 (F7 V+G0 V, ρ = 1.3”, Δmag = 0.7). From the analysis of these data, we can propose the existence of the fourth component with a late spectral type.

We present the first estimates of the relative and absolute parameters of the eclipsing binary EQ Boo based on a light-curve analysis ( P = 5.43 d , V = 8.8 m ). This star is simultaneously Component A of the visual binary ADS 9422 (spectral types F7V + G0V; separation of the components 1.3″; magnitude difference 0.7 m ). The derived disagreement between the components’ physical parameters and the assumption that they have the same age can be removed if there is a fourth, late-type star in the system. This is also able to explain the observed anomaly in the behavior of the O-C residuals at times of minima.

We have obtained the first UBV ( RI ) C photoelectric light curves of the recently discovered eclipsing binary BD +66 1663 = GSC 4479 412 ( P = 7.04 d , V = 10.14). We have derived relative and absolute parameters of the binary, and analyzed the interstellar extinction towards the object. Though the star is located in the field of the young open cluster Be 59, we demonstrate that it is not a member.

We have obtained the first U BV R photoelectric light curves for a recently discovered eclipsing binary with a period of 9.33 d and an appreciable eccentricity (e = 0.08). We have used these data to determine the photometric elements of the system for a model with two spherical stars with linear limb darkening. The high accuracy of the observations enabled determination of the absolute parameters of the components using available calibrations. The masses of the components are 1.28 and 1.08 M ⊙, and their ages are two billion years. The present orientation of the orbital ellipse is unfavorable for studies of the apsidal rotation, which is essentially due to relativistic effects.

New multicolor photoelectric observations of the highly eccentric (e=0.48) eclipsing star have enabled us to obtain well-founded absolute parameters of the system. The stars seem to be indistinguishable. The new theoretical rate of apsidal rotation follows from the new data.

A selective spectrophotometric method has been developed for the rapid analysis of polysiloxane preparations in solutions of chlorohydrocarbons from their absorption spectra in the IR region.