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P.A. Crowther (University College London), D.J. Hillier (University of Pittsburgh), A.W. Fullerton (Johns Hopkins, Baltimore), O. De Marco (American Museum of Natural History, NY)
Four extreme Magellanic Cloud O supergiants, spanning O4 to O9.7, are analysed using Far-UV (FUSE), UV (HST/IUE) and visual (VLT-UVES) spectroscopy and sophisticated line blanketed model atmospheres. From UVES datasets, we find stellar temperatures which are substantially lower than previously derived (by 10--20%), which are supported particularly by FUSE datasets, with important consequences for derived masses and luminosities. All program supergiants show strong evidence for CNO processing from optical and far-UV diagnostics, whilst FUSE datasets imply that either phosphorus is deficient in the Magellanic Clouds relative to other heavy elements, or O stars winds are already clumped at very small radii.
The author(s) of this abstract have provided an email address for comments about the abstract: pac@star.ucl.ac.uk