We continue our numerical analysis of the morphological and energetic influence of massive stars on their ambient interstellar medium for a 35 M _ { \sun } star that evolves from the main sequence through red supergiant and Wolf-Rayet phases , until it ultimately explodes as a supernova .
We find that structure formation in the circumstellar gas during the early main-sequence evolution occurs as in the 60 M _ { \sun } case but is much less pronounced because of the lower mechanical wind luminosity of the star .
Since on the other hand the shell-like structure of the H ii region is largely preserved , effects that rely on this symmetry become more important .
At the end of the stellar lifetime 1 % of the energy released as Lyman continuum radiation and stellar wind has been transferred to the circumstellar gas .
From this fraction 10 % is kinetic energy of bulk motion , 36 % is thermal energy , and the remaining 54 % is ionization energy of hydrogen .
The sweeping up of the slow red supergiant wind by the fast Wolf-Rayet wind produces remarkable morphological structures and emission signatures , which are compared with existing observations of the Wolf-Rayet bubble S308 , whose central star has probably evolved in a manner very similar to our model star .
Our model reproduces the correct order of magnitude of observed X-ray luminosity , the temperature of the emitting plasma as well as the limb brightening of the intensity profile .
This is remarkable , because current analytical and numerical models of Wolf-Rayet bubbles fail to consistently explain these features .
A key result is that almost the entire X-ray emission in this stage comes from the shell of red supergiant wind swept up by the shocked Wolf-Rayet wind rather than from the shocked Wolf-Rayet wind itself as hitherto assumed and modeled .
This offers a possible solution to what is called the “ missing wind problem ” of Wolf-Rayet bubbles .