Dynamic spectrum for Sk 80. The ordinate is sequential spectrum number, and the abscissa is velocity relative to the blue component of the doublet in the stellar rest frame. Each horizontal strip is a 5 minute subexposure normalized by the sample mean spectrum (shown at the bottom). At right is a temporal plot, which gives the relative time of each subexposure. The rest wavelengths of the O VI doublet and the S IV lines are indicated on the mean spectrum.