  We derive absolute dimensions for two early-type main sequence detached
eclipsing binaries in the young open cluster h Persei (NGC 869). V615 Persei
has a spectral type of B7V and a period of 13.7d. V618 Persei is A2V and has a
period of 6.4d. New ephemerides are calculated for both systems. The masses of
the component stars have been derived using high-resolution spectroscopy and
are 4.08+/-0.06 Msun and 3.18+/-0.05 Msun for V615 Per and 2.33+/-0.03 Msun and
1.56+/-0.02 Msun for V618 Per. The radii have been measured by fitting the
available light curves using EBOP and are 2.29+/-0.14 Rsun and 1.90+/-0.09 Rsun
for V615 Per and 1.64+/-0.07 Rsun and 1.32+/-0.07 Rsun for V618 Per. By
comparing the observed spectra of V615 Per to synthetic spectra from model
atmospheres we find that the effective temperatures of the two stars are
15000+/-500 K and 11000+/-500 K. The equatorial rotational velocities of the
primary and secondary components of V615 Per are 28+/-5 km/s and 8+/-5 km/s,
respectively. Both components of V618 Per rotate at 10+/-5 km/s. The equatorial
rotational velocities for synchronous rotation are about 10 km/s for all four
stars. The timescales for orbital circularisation for both systems, and the
timescale for rotational synchronisation of V615 Per, are much greater than the
age of h Per. Their negligible eccentricities and equatorial rotational
velocities therefore support the hypothesis that they were formed by 'delayed
breakup'. We have compared the radii of these stars to models by the Granada
and the Padova groups for stars of the same masses but different compositions.
We conclude that the metallicity of the stars is about Z=0.01. This appears to
be the first estimate of the bulk metallicity of h Per. Recent photometric
studies have assumed a solar metallicity so their results should be reviewed.
