SPACE TELESCOPE IMAGING SPECTROGRAPH OBSERVATIONS OF THE INTERSTELLARVELOCITY STRUCTURE AND CHEMICAL-COMPOSITION TOWARD THE CARINA NEBULA

We have observed the O-type star CPD -59 degrees 2603 in the Carina Ne bula with the Space Telescope Imaging Spectrograph near-UV and far-UV high-resolution echelles, at a resolving power of similar to 110,000 ( FWHM) and S/N similar to 30. This sight line has complex velocity and excitation structure in the interstellar absorption lines, correspondi ng to three distinct regions: very high velocity components formed wit hin the nebula; a warm, expanding H II region; and cool, low-velocity gas near the Sun. The ME I and Mg II profiles show many components, wi th velocities extending from -235 to +123 kms(-1). We have derived phy sical conditions in the expanding H II region from Si IV doublet and t he excited fine-structure lines of C I. Heavy elements (O, Ni, Cu, Ga) are present in the low-velocity gas, and their abundances indicate de pletions consistent with nearby, cool diffuse clouds. (CO)-C-12 is det ected in just one low-velocity component, suggesting different amounts of processing among the clouds near the Sun.