A hydrodynamical model of the circumstellar bubble created by two
  massive stars
  Numerical models of the wind-blown bubble of massive stars usually only
account for the wind of a single star. However, since massive stars are usually
formed in clusters, it would be more realistic to follow the evolution of a
bubble created by several stars. We develope a two-dimensional (2D) model of
the circumstellar bubble created by two massive stars, a 40 solar mass star and
a 25 solar mass star, and follow its evolution. The stars are separated by
approximately 16 pc and surrounded by a cold medium with a density of 20
particles per cubic cm. We use the MPI-AMRVAC hydrodynamics code to solve the
conservation equations of hydrodynamics on a 2D cylindrical grid using
time-dependent models for the wind parameters of the two stars. At the end of
the stellar evolution (4.5 and 7.0 million years for the 40 and 25 solar mass
stars, respectively), we simulate the supernova explosion of each star. Each
star initially creates its own bubble. However, as the bubbles expand they
merge, creating a combined, aspherical bubble. The combined bubble evolves over
time, influenced by the stellar winds and supernova explosions. The evolution
of a wind-blown bubble created by two stars deviates from that of the bubbles
around single stars. In particular, once one of the stars has exploded, the
bubble is too large for the wind of the remaining star to maintain and the
outer shell starts to disintegrate. The lack of thermal pressure inside the
bubble also changes the behavior of circumstellar features close to the
remaining star. The supernovae are contained inside the bubble, which reflects
part of the energy back into the circumstellar medium.
