Interactions of Massive Stars with the Interstellar Medium: Bow Shocks and Superbubbles

Stellar winds and supernovae from massive stars carry most of the energy transferred from stars to the interstellar medium. The structures created by these processes reveal glimpses of the movement of mass between stars and the interstellar gas in the galactic ecological cycle. In this thesis, I model two such structures: bow shocks and superbubbles. Multiple supernovae and winds from OB associations carve large holes filled with hot gas in the galactic disk. These superbubbles sweep up thin, cold, dense shells that eventually grow large enough to blow out of the disk, venting hot gas into the galactic halo. To model superbubbles, I first analytically describe the blast waves from supernovae within them, showing they become subsonic before reaching the walls or cooling radiatively. I then use the Kompaneets or thin-shell approximation to numerically model the growth of superbubbles in stratified disks until they become Rayleigh -Taylor unstable. I show that hot gas does not escape when clouds pierce the shell. I then use ZEUS, a two-dimensional hydrodynamics code, to follow the breakup of the shell. I show that the Kompaneets approximation works well. I explain the differences between my results and previous models. I find that most of the mass of the superbubble shell remains in the plane, with 5% of it accelerating upward. I suggest that the low galactic halo actually consists of a froth of merged superbubbles. Considering stars with strong winds leads to an explanation for ultracompact H sc II regions (UCHRs). Recent surveys show that they are far too common to be simply young H sc II regions. I propose that most UCHRs are trapped in bow shocks swept up by the winds of massive stars moving supersonically through molecular clouds. I use a thin -shell approximation to find the shape of such bow shocks. I produce simulated maps and compare them to G12.21 - 0.01, G29.96 - 0.02, G34.26 + 0.15, and G43.89 - 0.78. I show the velocity structure of the region, predicting recombination line profiles and proper motions of masers in the shell. I give criteria for distinguishing between UCHRs trapped in bow shocks and truly young regions.