The strong stellar winds of massive stars, and especially of their evolved representatives known as Wolf-Rayet stars, convey huge amounts of kinetic power. When these winds collide with the interstellar medium (significantly made of the material ejected at previous evolution phases of the star), a termination shock is produced. Beside the formation of so-called stellar bubbles filled with hot gas, the shock itself is especially interesting in the context of particle-accelerating environments. The action of Diffusive Shock Acceleration in these environments can be revealed by the measurement of non-thermal radiation. A very good example is that of the stellar bubble G2.4+1.4 surrounding the oxygen-rich Wolf-Rayet star WR102. Radio observations with the GMRT revealed a strong signature for synchrotron radio emission, confirming the capability of the shocks produced by single star winds to accelerate particles (Prajapati et al. 2019).

Distribution of the spectral index across shock forming the G2.4+1.4 bubble. Some regions display clear non-thermal signatures (Prajapati et al. 2019).