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J. Zsargo, A. Fullerton (Department of Physics and Astronomy, The Johns Hopkins University), D. Massa (Emergent IT, NASA Goddard Space Flight Center)
One goal of the Far Ultraviolet Spectroscopic Explorer ( FUSE) mission is to study the formation of the O~{\small VI} superion in the stellar winds of Galactic and Magellanic O- and B-type stars. As part of this ongoing effort, we have been analyzing FUSE spectra of a large number of early B-type stars, located both in the Galactic halo and the disk. The objective of this investigation is to determine how far into the domain of the B-type stars stellar O~{\small VI} persists, and correlate its occurrence with other stellar parameters, particularly luminosity.
By comparing the putative wind features in the O~{\small VI} absorption with the N~{\small V}, Si~{\small IV} and C~{\small IV} wind profiles seen in the IUE and STIS spectra, we have definitely identified wind features in the O~{\small VI} absorption of three early B-type giants and supergiants (B0.5II-I, BN1Ib, B1II). Approximately half a dozen others show similar features that we could not yet clearly attribute to the wind. Our preliminary results suggest that the signatures of the wind in O~{\small VI} appear in the spectra of giants and supergiants and not in the main-sequence B-type stars, at or near the terminal velocity of the wind.
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.
The author(s) of this abstract have provided an email address for comments about the abstract: jzsargo@pha.jhu.edu