Dust in stellar wind bow shocks

A number of high velocity O stars have associated parsec-sized structure visible in the IRAS infrared. They can most readily be explained as the dense shells of stellar wind bow shocks. The IR emission arises from starlight-heated post-shock dust, and possibly also from ionic lines. Emission from pre-shock dust is often seen as well, and allows in principle the empirical determination of the effects of shocks on dust. Since the observed bow shocks span a range of velocities a comparison with theories for shock destruction of dust is possible.