Betelgeuse workshop 2012 The physics of red supergiants: recent advances and open questions location:Paris, France date:26-29 November 2012
We present hydrodynamical simulations of the interaction between the stellar wind of α-Orionis and the interstellar gas. In particular we focus our efforts on reproducing the multiple arc structure of the bow-shock that was observed with Herschel. We do this by varying the mass loss rate of the star over a period of 10 000 years, representing the effect of thermal pulses. We find that the effect of repeated collisions between high density shells and the wind termination shock can create multiple arc-like structures in the inner part of the bow-shock region. This may explain the arcs seen in the observations. Unlike the observed bow-shock of α-Orionis, our simulations show strong instabilities at the contact discontinuity between the shocked wind and the shocked interstellar medium. This can be an indication of the age of the bow-shock, which may be to young to have formed the instabilities.