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D. Massa (Emergent IT), A.W. Fullerton (Univ. Victoria, JHU)
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of 10 LMC O7-9 stars. The wind lines in the FUSE wavelength range are analyzed using the Sobolev with Exact Integration (SEI) model. These lines include O VI, P V, C III, N III and both S IV and S VI in several cases. Our analysis allows us to determine the line optical depths as a function of velocity. For stars with well developed but unsaturated S IV and S VI, the results provide a unique opportunity to determine how the ionization of O star winds depends on velocity and, presumably, position in the wind flow. Since all of the program stars are at effectively the same distance, the sample can also be used to establish how the total optical depth of different wind lines and their velocity structure respond to stellar luminosity and spectral class. In addition, the wind lines in the FUSE wavelength range are shown to provide valuable diagnostics for chemical peculiarities.
This work is based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.