Observations of the Interstellar Medium in the Magellanic Bridge
Abstract
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-1. Interstellar absorption by the Magellanic Bridge at vLSR~200 km s-1 is 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+3)/N(Si+3)~1.9, similar to that inferred for collisionally ionized Galactic cloud interfaces at temperatures ~105 K. We identify substructure in the stronger interstellar lines, with a broad component (FWHM~20 km s-1) at ~179 km s-1 and a sharp component (FWHM~11 km s-1) at 198 km s-1. The abundance analysis for these clouds indicates that the feature at 198 km s-1 consists of a low electron density, mainly neutral gas that may be associated with an interface responsible for the highly ionized gas. The 179 km s-1 cloud consists of warmer, lower density gas that is partially ionized. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2001
- DOI:
- 10.1086/320221
- arXiv:
- arXiv:astro-ph/0101548
- Bibcode:
- 2001ApJ...551..781L
- Keywords:
-
- Galaxies: Abundances;
- ISM: Abundances;
- ISM: Structure;
- Galaxies: Magellanic Clouds;
- Astrophysics
- E-Print:
- Accepted for publication in ApJ (April 10, 2001). Minor corrections in Figures 1 and 3, and in references