  We present a detailed study of the G0V detached eclipsing binary EW Ori,
based on new photometric and spectroscopic observations. Masses and radii that
are precise to 0.9% and 0.5%, respectively, have been established for both
components. The 1.12 Msun secondary component reveals weak Ca II H and K
emission and is probably mildly active; no signs of activity are seen for the
1.17 Msun primary. We derive an [Fe/H] abundance of +0.05 +/- 0.09 and similar
abundances for Si, Ca, Sc, Ti, Cr, and Ni. Yonsai-Yale and Granada solar-scaled
evolutionary models for the observed metal abundance reproduce the components
fairly well at an age of approx. 2 Gyr. Perfect agreement is, however, obtained
at an age of 2.3 Gyr for a combination of a) a slight downwards adjustment of
the envelope mixing length parameter for the secondary, as seen for other
active solar-type stars, and b) a slightly lower helium content than prescribed
by the Y-Z relations adopted for the standard model grids. The orbit is
eccentric (e = 0.0758 +/- 0.0020), and apsidal motion with a 62% relativistic
contribution has been detected. The apsidal motion period is U = 16300 +/- 3900
yr, and the inferred mean central density concentration coefficient, log(k_2) =
-1.66 +/- 0.30, agrees marginally with model predictions. The measured
rotational velocities, 9.0 +/- 0.7 (primary) and 8.8 +/- 0.6 (secondary) km/s,
are in agreement with both the synchronous velocities and the theoretically
predicted pseudo-synchronous velocities. Finally, the distance (175 +/- 7 pc),
age, and center-of mass velocity (6 km/s) exclude suggested membership of the
open cluster Collinder 70. EW Ori now belongs to the small group of solar-type
eclipsing binaries with well-established astrophysical properties.
