  Using recent spectroscopic observations, we show that the triple system AO
Vel with an eclipsing BpSi primary is in fact a remarkable quadruple system
formed by two double-lined spectroscopic binaries with components close to the
ZAMS. All available data have been reanalyzed to derive proper orbital
parameters for both binary systems and to calculate absolute parameters of the
eclipsing system. For the first time, direct determination of the radius and
the mass have been obtained for a BpSi star. The study of the physical
parameters of this unique system is especially important since it can be used
as a test of evolutionary models for very young stars of intermediate mass.
