Context : Double-lined , detached eclipsing binaries are our main source for accurate stellar masses and radii .
This paper is the first in a series with focus on the upper half of the main-sequence band and tests of 1–2 M _ { \sun } evolutionary models .

Aims : We aim to determine absolute dimensions and abundances for the detached eclipsing binary V1130 Tau , and to perform a detailed comparison with results from recent stellar evolutionary models .

Methods : uvby light curves and uvby \beta standard photometry have been obtained with the Strömgren Automatic Telescope , and high-resolution spectra have been acquired at the FEROS spectrograph ; both are ESO , La Silla facilities .
We have applied the Wilson-Devinney model for the photometric analysis , spectroscopic elements are based on radial velocities measured via broadening functions , and [ \mathrm { Fe / H } ] abundances have been determined from synthetic spectra and uvby calibrations .

Results : V1130 Tau is a bright ( m _ { V } = 6.56 ) , nearby ( 71 \pm 2 pc ) detached system with a circular orbit ( P = 0 \aas@@fstack { d } 80 ) .
The components are deformed with filling factors above 0.9 .
Their masses and radii have been established to 0.6–0.7 % .
We derive a [ \mathrm { Fe / H } ] abundance of -0.25 \pm 0.10 .
The measured rotational velocities , 92.4 \pm 1.1 ( primary ) and 104.7 \pm 2.7 ( secondary ) km s ^ { -1 } , are in fair agreement with synchronization .
The larger 1.39 M _ { \sun } secondary component has evolved to the middle of the main-sequence band and is slightly cooler than the 1.31 M _ { \sun } primary .
Yonsai-Yale , BaSTI , and Granada evolutionary models for the observed metal abundance and a ’ normal ’ He content of Y = 0.25 - 0.26 , marginally reproduce the components at ages between 1.8 and 2.1 Gyr .
All such models are , however , systematically about 200 K hotter than observed and predict ages for the more massive component , which are systematically higher than for the less massive component .
These trends can not be removed by adjusting the amount of core overshoot or envelope convection level , or by including rotation in the model calculations .
They may be due to proximity effects in V1130 Tau , but on the other hand , we find excellent agreement for 2.5–2.8 Gyr Granada models with a slightly lower Y of 0.23–0.24 .

Conclusions : V1130 Tau is a valuable addition to the very few well-studied 1–2 M _ { \sun } binaries with component ( s ) in the upper half of the main-sequence band , or beyond .
The stars are not evolved enough to provide new information on the dependence of core overshoot on mass ( and abundance ) , but might - together with a larger sample of well-detached systems - be useful for further tuning of the helium enrichment law .
Analyses of such systems are in progress .