Rediscussion of eclipsing binaries. XIII. DI Her, a B-type system with an eccentric orbit.

The properties of the components of the detached middle B-type binary, DI Her, are derived from a new series of Lick spectrograms and the Martynov-Khalliulin photometry. The components lie along the lower envelope of the distributions of stars with well determined masses and radii in the mass-radius and color-absolute magnitude planes. They are also close to the empirical zero-age main sequence based on open clusters.