Article

# Radiation-Hydrodynamic Models of the evolving Circumstellar Medium around Massive Stars

The Astrophysical Journal (Impact Factor: 6.28). 06/2011; 737(2). DOI: 10.1088/0004-637X/737/2/100
Source: arXiv

ABSTRACT We study the evolution of the interstellar and circumstellar media around
massive stars (M > 40M_{\odot}) from the main sequence through to the
Wolf-Rayet stage by means of radiationhydrodynamic simulations. We use publicly
available stellar evolution models to investigate the different possible
structures that can form in the stellar wind bubbles around Wolf-Rayet stars.
We find significant differences between models with and without stellar
rotation, and between models from different authors. More specifically, we find
that the main ingredients in the formation of structures in the Wolf-Rayet wind
bubbles are the duration of the Red Supergiant (or Luminous Blue Variable)
phase, the amount of mass lost, and the wind velocity during this phase, in
agreement with previous authors. Thermal conduction is also included in our
models. We find that main-sequence bubbles with thermal conduction are slightly
smaller, due to extra cooling which reduces the pressure in the hot, shocked
bubble, but that thermal conduction does not appear to significantly influence
the formation of structures in post-main-sequence bubbles. Finally, we study
the predicted X-ray emission from the models and compare our results with
observations of the Wolf-Rayet bubbles S\,308, NGC\,6888, and RCW\,58. We find
that bubbles composed primarily of clumps have reduced X-ray luminosity and
very soft spectra, while bubbles with shells correspond more closely to
observations.

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