ULTRAVIOLET-ABSORPTION LINES FROM HIGH-VELOCITY GAS IN THE VELA SUPERNOVA REMNANT - NEW INSIGHTS FROM SPACE TELESCOPE IMAGING SPECTROGRAPH ECHELLE OBSERVATIONS OF HD-72089

The star HD 72089 is located behind the Vela supernova remnant and sho ws a complex array of high-and low-velocity interstellar absorption fe atures arising from shocked clouds. A spectrum of this star was record ed over the wavelength range 1196.4-1397.2 Angstrom at a resolving pow er of lambda/Delta lambda = 110,000 and a signal-to-noise ratio of 32 by the Space Telescope Imaging Spectrograph on the Hubble Space Telesc ope. We have identified seven narrow components of C I and have measur ed their relative populations in excited fine-structure levels. Broade r features at heliocentric velocities ranging from -70 to 130 km s(-1) are seen in C II, N I, O I, Si II, S II, and Ni II. In the high-veloc ity components, the unusually low abundances of N I and O I, relative to S II and Si II, suggest that these elements may be preferentially i onized to higher stages by radiation from hot gas immediately behind t he shock fronts.