X-ray emission in wind instability simulations

We estimate X-ray emission by shock-heated regions in hot star winds, using temperature and density profiles calculated by time-dependent dynamical models; the shocks result from the instability of the line scattering force that drives the wind. For main sequence late O and early B stars, the model X-ray flux is generally well below the observed flux, though the shape of the model spectrum is approximately consistent with observations. For the early O supergiant Pup, the model spectral shape again agrees with observation; the total flux predicted by models is well above the observed flux, though significant uncertainties remain.