  delta Velorum is a nearby (24pc) triple stellar system, containing a close,
eclipsing binary (Aa, Ab) discovered in 2000. Multiple systems provide an
opportunity to determine the set of fundamental parameters (mass, luminosity,
size and chemical composition) of coeval stars. These parameters can be
obtained with particular precision in the case of eclipsing binaries; for delta
Velorum's components (Aa, Ab) this potential has however not yet been
exploited. We have analyzed interferometric observations of the close binary
(Aa, Ab), obtained with the VINCI instrument and two VLTI siderostats. The
measurements, which resolve the two components for the first time, are fitted
onto the simple model of two uniformly bright, spherical stars. The
observations suggest that Aa and Ab have larger diameters than expected if they
were on the main sequence, and that they are, thus, in a later evolutionary
state.

Astrophysics