2004ApJ...606..900S

We present Far Ultraviolet Spectroscopic Explorer (FUSE) data on O VI absorption lines observed toward nine stars behind the Vela supernova remnant (SNR). The O VI observations are compared with International Ultraviolet Explorer (IUE) observations of C IV absorption toward the same stars. All of these stars are B stars, which generally have complex continua, making the extraction of absorption lines difficult. However, four of the stars, HD 72088, HD 72089, HD 72350, and HD 72537, are rapid rotators (vsini≳150 km/s), making the derivation of absorption column densities much easier. We present O VI and C IV column densities for the ``main component'' (i.e., the low-velocity component) for these stars. In the FUSE spectra of three of the rapid rotators (HD 72088, HD 72089, and HD 72537) we find high-velocity components of O VI at ∼150 km/s that we attribute to the SNR shock. HD 72350 has very strong H₂absorption, which obscures any possible high-velocity O VI absorption. To detect the high-velocity O VI absorption in HD 72088 requires employing a technique for removing the H₂line at 1032.35 Å (121.6 km/s relative to O VI). The O VI data are consistent with steady radiative shock models with v_s~150 km/s, but we do not detect C IV at the same velocities. Instead we find high-velocity C IV at lower velocities (∼100 km/s). We discuss the implications of our results for models of the evolution of the Vela SNR.