Masses, radii, temperatures and abundances are the fundamental parameters upon which the properties and evolution of stars depend. The only source for direct determination of the mass of a star is the effect of its gravitational attraction on other stars. The most precise method to calculate the mass and the other fundamental parameters of a star (radius, temperature, and abundances) is to combine photometric and spectroscopic observations applied to eclipsing binaries.
From the spectroscopic radial velocity curve, we apportion the individual masses of the components modulated by a factor which depends on the angle of inclination of the orbit i. Once this angle is determined (from the photometric light curve), the masses of the two components can be calculated. Also, from the velocity curve, the surface gravity, eccentricity and orientation of the orbit can be deduced.
The geometric parameters (inclination angle, relative radii, etc.) can only be computed from very well-defined light curves. Specially favourable are the binary systems with total or nearly-total eclipses and soft mutual interaction between components. The radiative properties of the components (effective temperature, etc.) can be estimated from photometric calibrations and light curves.
Thus, good-quality photometric and radial velocity curves of favourable eclipsing binaries, allow us to deduce the fundamental astrophysical quantities accurately. This task has been undertaken by the astronomic community with good results, specially for early-type stars. However, more accurate astrophysical absolute parameter determinations are needed for late-type stars. In the intermediate and low mass-range, where the population of stars becomes more denser, the calibration of fundamental parameters critically depends on the values of a very small number of stars.
This paper is concerned with this particular topic. We present a detailed
analysis and absolute parameters determination of the main sequence late-type
detached binary system ZZ UMa, using the first available 
light
curves and very recent spectroscopic determination of masses.
ZZ UMa was firstly classified as eclipsing binary by Kippenhahn in Geyer et al. (1955). Its photographic light curve is of Algol type (Döppner 1962). Mallama (1980) calculated ephemerides 2441499.5953+2.2992629 E. The photoelectric curves of ZZ UMa published by Lavrona & Lavrov (1988), show that reflection and ellipticity effects are small. The secondary star was classified as G6-G8 by Janiashvili & Lavrov (1989), which is in agreement with our preliminary analysis (Clement et al. 1993).