Disentangling effective temperatures of individual eclipsing binary components by means of color-index constraining

Eclipsing binary stars are gratifying objects because of their unique geometrical properties upon which all important physical parameters such as masses, radii, temperatures, luminosities and distance may be obtained in absolute scale. This poses strict demand on the model to be free of systematic effects that would influence the results later used for calibrations, catalogs and evolution theory. We present an objective scheme of obtaining individual temperatures of both binary system components by means of color-index constraining, with the only requirement that the observational data-set is acquired in a standard photometric system. We show that for a modest case of two similar main-sequence components the erroneous approach of assuming the temperature of the primary star from the color index yields temperatures which are systematically wrong by ~100K.Comment: 6 pages, 3 figures, 1 table; to appear in proceedings of the Close Binaries in the 21st Century conference in Syros, Greec

Spectroscopy and BVI photometry of the young open cluster NGC 6604

BVI photometry (from South Africa Astron. Obs.), Echelle high resolution spectroscopy and AFOSC integral field spectroscopy (from Asiago, Italy) of the young open cluster NGC 6604 are presented. Age, distance, reddening, membership, radial and rotational velocities are derived and discussed. An age of 5 million years, a distance of 1.7 kpc and a reddening E(B-V)=1.02 are found. The cluster radial velocity is in agreement with the Hron (1987) model for the Galaxy disk rotation. Pre-ZAMS objects are not present down to M_V = +1.5 mag.Comment: accepted in Astron.Astrophys.Suppl. Figure 2 is degraded in resolutio