Soft X-ray spectra of stellar-wind bubbles

X-ray spectra are calculated in the ionization-equilibrium approximation for model gas bubbles in the shell evolutionary phase, blown in the interstellar medium by a stellar wind. Tabulated values cover the 83-4000 eV photon energy range at Delta-E/E = 0.1 resolution, and indicate the effect of interstellar absorption on the bubble spectrum. The energy-integrated flux is tabulated against the column density N(H) of the intervening medium and the central temperature T(0) of the decelerated-wind zone. A bubble spectrum can be distinguished from that of isothermal gas (corrected for absorption): it will be significantly softer, and in particular will fall off more gradually toward low E. Both T(0) and N(H) will be underestimated if an isothermal model is used, and the bubble's X-ray luminosity will be seriously understated (by at least an order of magnitude) for the Cygnus Superbubble.