Observations of the Interstellar Medium in the Magellanic Bridge

We present ultraviolet and optical spectra of DI 1388, a young star in the Magellanic Bridge, a region of gas between the Small and Large Magellanic Clouds. The data have signal-to-noise ratios of 20–45 and a spectral resolution of 6.5 km s. Interstellar absorption by the Magellanic Bridge at vLSR ≈ 200 km sis visible in the lines of C I, C II, C II*, C IV, N I, O I, Al II, Si II, Si III, Si IV, S II, Ca II, Fe II, and Ni II. The relative gas-phase abundances of C II, N I, O I, Al II, Si II, Fe II, and Ni II with respect to S II are similar to those found in Galactic halo clouds, despite a significantly lower metallicity in the Magellanic Bridge. The higher ionization species in the cloud have a column density ratio N(C)/N(Si) ∼ 1.9, similar to that inferred for collisionally ionized Galactic cloud interfaces at temperatures ∼ 10 K. We identify sub-structure in the stronger interstellar lines, with a broad component (FWHM ∼ 20 km s) at ∼ 179 km sand a sharp component (FWHM ∼ 11 km s) at 198 km s. The abundance analysis for these clouds indicates that the feature at 198 km sconsists of a low electron density, mainly neutral gas that may be associated with an interface responsible for the highly ionized gas. The 179 km scloud consists of warmer, lower density gas that is partially ionized. Subject headings: Galaxies: abundances — ISM: abundances — Magellanic Bridge — ISM: structure