  We are carrying out an international, multi-wavelength program to determine
the fundamental properties and independent distance estimates of selected
eclipsing binaries in the LMC and SMC. Eclipsing binaries with well-defined
double-line radial velocity curves and light curves provide valuable
information on orbital and physical properties of their component stars. The
study of stars in the LMC and SMC where the metal abundances are significantly
lower than solar provides an important opportunity to test stellar atmosphere,
interior and evolution models, and opacities. For the first time, we can also
measure direct M-L relations for stars outside our Galaxy. In this paper we
concentrate on the determination of the orbital and physical properties of HV
2274 from analyses of light curves and new radial velocity curves formed from
HST/GHRS observations. From UV/optical spectrophotometry of HV 2274 obtained
with HST/FOS, the temperatures and the metallicity of the stars were found, as
well as the interstellar extinction of the system. The values of mass, absolute
radius, and effective temperature, for the primary and secondary stars are:
12.2(7) Mo, 9.9(2) Ro, 23000(180) K, and 11.4(7) Mo, 9.0(2) Ro, 23110(180) K,
respectively. The age of the system (17(2) Myr), helium abundance (Y=0.26(3))
and a lower limit of the convective core overshooting parameter of 0.2 were
obtained from fitting the stellar data with evolution models. The apsidal
motion analysis corroborates that some amount of convective overshooting
(0.2-0.5) is needed.
