  We have recomputed the kinematic properties of several of dozens nearby
stars, to try to verify if Castor has a cohort of stars sharing the same space
motion and age. We used kinematics, the location of the stars in CM diagrams,
their lithium abundances, and their activity, to establish that the moving
group seems to be real and to reject several stars which were believed to be
part of this group. Of the initial 26 stars, we show that probably only 16
stars are physically associated. The moving group contains several A spectral
type stars. Among them, Vega and Fomalhaut, two of the prototypes of the beta
Pic type stars. Since this association includes several late spectral type
stars, we used their properties to estimate their age and, therefore, the age
of the group and that of Vega and Fomalhaut. Our estimate for that age is
200$\pm$100 Myr.

Astrophysics