THE TRIPLE SYSTEM HD-165590 - A SPECTROSCOPIC AND PHOTOMETRIC-STUDY

A detailed study of the system V772 Her = HD 165590 = ADS 11060 AB is presented. The three identified components are found to be late type stars close to the zero-age main sequence with high rotational velocities. Spectroscopic observations allowed a quantitative determination of stellar activity indicators for the two members of the close binary as well as for the visual companion. An estimation of the most relevant physical parameters has been derived from the colour indices of each of the components and the close system has been found to be an eclipsing binary. This additional source of information combined with published measures of radial velocities, provides the absolute dimensions of the component stars (1.1 and 0.6 solar masses, and 0.9 and 0.6 solar radii) which confirm that the system is very little evolved. Moreover, a distance of 32 +/- 4 parsecs has been found to V772 Her in good agreement with available trigonometric determinations. Finally, we have compared these results with evolutionary models for main sequence stars of solar chemical composition.