We report the detection of the H i line at 21 cm in the direction of \alpha Ori with the Nançay Radiotelescope and with the Very Large Array .

The observations confirm the previous detection of H i emission centered on \alpha Ori , but additionally reveal for the first time a quasi-stationary detached shell of neutral atomic hydrogen \sim 4 ^ { \prime } in diameter ( 0.24 pc at a distance of 200 pc ) .
The detached shell appears elongated in a direction opposite to the star ’ s space motion .

A simple model shows that this detached atomic gas shell can result from the collision of the stellar wind from \alpha Ori with the local interstellar medium ( ISM ) .
It implies that \alpha Ori has been losing matter at a rate of \sim 1.2 \times 10 ^ { -6 } M _ { \odot } yr ^ { -1 } for the past 8 \times 10 ^ { 4 } years .

In addition , we report the detection of atomic hydrogen associated with the far-infrared arc located 6 ^ { \prime } north-east of \alpha Ori , that has been suggested to trace the bow shock resulting from the motion of the star through the ISM .
We report also the detection by the Galaxy Evolution Explorer ( GALEX ) of a far-UV counterpart to this arc .