  We present a study of the radio emission from a massive runaway star. The
star forms a bow shock that is clearly observed in the infrared. We have
performed VLA observations under the assumption that the reverse shock in the
stellar wind might accelerate charged particles up to relativistic energies.
Non-thermal radio emission of synchrotron origin has been detected, confirming
the hypothesis. We have then modeled the system and we predict a spectral
energy distribution that extends up to gamma-rays. Under some simplifying
assumptions, we find that the intensity at high energies is too low to be
detected by current instruments, but the future Cherenkov Telescope Array might
detect the source.
