Far Ultraviolet Spectroscopic Explorer Spectroscopy of the O VI Resonance Doublet in Sand 2 (WO)
Sonneborn, G.; Hillier, D. J.; Willis, A. J.; Barlow, M. J.; Hutchings, J. B.; Fullerton, A. W.; De Marco, O.; Massa, D. L.; Crowther, Paul A.; Morton, D. C.; Dessart, L.; Brownsberger, K.
United Kingdom, Canada, United States
Abstract
We present Far Ultraviolet Spectroscopic Explorer spectroscopy of Sand 2, an LMC WO-type Wolf-Rayet star, revealing the O VI resonance P Cygni doublet at 1032-1038 Å. These data are combined with Hubble Space Telescope Faint Object Spectrograph ultraviolet and Mount Stromlo 2.3 m optical spectroscopy and analyzed using a spherical, non-LTE, line-blanketed code. Our study reveals exceptional stellar parameters: T*~150,000 K, v∞=4100 km s-1, log(L/Lsolar)=5.3, and M=1×10-5 Msolar yr-1, if we adopt a volume filling factor of 10%. Elemental abundances of C/He~0.7+/-0.2 and O/He~0.15+0.10-0.05 by number qualitatively support previous recombination line studies. We confirm that Sand 2 is more chemically enriched in carbon than LMC WC stars and that it is expected to undergo a supernova explosion within the next 5×104 yr.