High resolution X-ray spectroscopy of bright O type stars
L. M. Oskinova, A. Feldmeier, W.-R. Hamann
In this paper we reproduce the shape of X-ray emission lines observed in single non-magnetic O stars using a clumped wind model. The Chandra {\sc hetgs/meg} spectra of $\zeta$~Pup,\,$\xi$~Per,\,$\zeta$~Ori, and $\zeta$~Oph are analyzed. From the line ratios of He-like ions the X-ray line formation regions are constrained to be located in the acceleration part of the stellar winds. To calculate the wind opacity at X-ray wavelengths for each star we use the NLTE stellar atmosphere model PoWR. The stellar parameters and wind opacities are then used as input parameters for our 2-D numerical model of a stochastic, inhomogeneous wind consisting of radially compressed shell fragments. The model line profiles are symmetric, blueshifted, and similar across the spectrum, exactly as observed in the spectra of our sample stars. We conclude that X-ray emission line profiles observed in O stars can be explained by the radiative transfer in clumped stellar winds.
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