We have recomputed the kinematic properties of several of dozens nearby stars , to try to verify if Castor ( \alpha Gem ) indeed has a cohort of stars sharing the same space motion and age .
We used kinematics , the location of the stars in Color-Magnitude 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 .
If these stars are coeval , their different levels of IR emission suggest that the time scale for the formation of planets is not universal .
Due to the age of the group , these IR excesses would appear as a consequence of collisions and sublimation of larger bodies and they would not arise from protoplanetary structures .

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 .