FAR-ULTRAVIOLET ABSORPTION-LINES IN THE REMNANT OF SN-1006

We have obtained a far-ultraviolet spectrum (1150-1600 ii) of a hot su bdwarf star behind the remnant of supernova 1006 with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope. The high-quality sp ectrum is used to test previous identifications of the strong absorpti on features discovered with the International Ultraviolet Explorer. Th ese features have FWHM = 4000 (+/-300) km s(-1) and are not at the res t wavelengths of known interstellar lines, as opposed to the broader ( similar to 8000 km s(-1) FWHM) Fe II lines from the remnant centered a t 0 km s(-1) in near-UV FOS spectra. We confirm that the broad absorpt ion features are principally due to redshifted Si II, Si III, and Si I v lines, which are centered at a radial velocity of 5100 (+/-200) km s (-1). The Si II lambda 1260.4 profile is asymmetric, with a nearly fla t core and sharp red wing, unlike the Si II lambda 1526.7 and Si IV la mbda lambda 1393.8, 1402.8 profiles. One possible explanation is addit ional absorption from another species. Previous work has suggested tha t S II lambda lambda 1250.6, 1253.8, 1259.5 at a radial velocity of si milar to 6000 km s(-1) is responsible, but this would require a sulfur -to-silicon abundance ratio that is at least a factor of 10 higher tha n expected. Another possible explanation is that the Si II and Si IV p rofiles are intrinsically different, but this does not explain the sym metric (albeit weaker) Si II lambda 1526.7 profile.