EDP Sciences
Free access
Volume 405, Number 3, July III 2003
Page(s) 1043 - 1056
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030601

A&A 405, 1043-1056 (2003)
DOI: 10.1051/0004-6361:20030601

A search for OVI in the winds of B-type stars

J. Zsargó1, A. W. Fullerton1, 2, N. Lehner1, 3 and D. Massa4

1  Dept. of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
2  Dept. of Physics and Astronomy, University of Victoria, PO Box 3055, Victoria, BC, V8W 3P6, Canada
3  Present Address: Dept. of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53706, USA
4  SGT Inc., Code 681.0, NASA's Goddard Space Flight Center, Greenbelt, MD 20771, USA

(Received 29 January 2003 / Accepted 18 April 2003)

We have conducted a survey of FUSE spectra of 235 Galactic B-type stars in order to determine the boundaries in the H-R diagram for the production of the superion $\ion{O}{vi}$ in their winds. By comparing the locations and morphology of otherwise unidentified absorption features in the vicinity of the $\ion{O}{vi}$ resonance doublet with the bona fide wind profiles seen in archival IUE spectra of the resonance lines of $\ion{N}{v}$, $\ion{Si}{iv}$ and $\ion{C}{iv}$, we were able to detect blueshifted $\ion{O}{vi}$ lines in the spectra of giant and supergiant stars with temperature classes as late as B1. No features attributable to $\ion{O}{vi}$ were detected in dwarfs later than B0, or in stars of any luminosity class later than B1, although our ability to recognize weak absorption features in these stars is severely restricted by blending with photospheric and interstellar features. We discuss evidence that the ratio of the ion fractions of $\ion{O}{vi}$ and $\ion{N}{v}$ is substantially different in the winds of early B-type stars than O-type stars.

Key words: stars : early-type -- stars : mass-loss -- ultraviolet : general

Offprint request: J. Zsargó, jzsargo@astro.phyast.pitt.edu

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