  We report here the first observations of a rapidly rotating Be star, $\alpha$
Eridani, using Earth-rotation synthesis on the Very Large Telescope (VLT)
Interferometer. Our measures correspond to a $2a/2b = 1.56\pm0.05$ apparent
oblate star, $2a$ and $2b$ being the equivalent uniform disc angular diameters
in the equatorial and polar direction. Considering the presence of a
circumstellar envelope (CSE) we argue that our measurement corresponds to a
truly distorted star since $\alpha$ Eridani exhibited negligible H$\alpha$
emission during the interferometric observations. In this framework we conclude
that the commonly adopted Roche approximation (uniform rotation and centrally
condensed mass) should not apply to $\alpha$ Eridani. This result opens new
perspectives to basic astrophysical problems, such as rotationally enhanced
mass loss and internal angular momentum distribution. In addition to its
intimate relation with magnetism and pulsation, rapid rotation thus provides a
key to the Be phenomenon: one of the outstanding non-resolved problems in
stellar physics.
