An Atlas ofFar Ultraviolet Spectroscopic ExplorerSight Lines toward the Magellanic Clouds

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Abstract
We present an atlas of 57 Large Magellanic Cloud (LMC) and 37 Small Magellanic Cloud (SMC) observations obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. The atlas highlights 12 interstellar absorption-line transitions at a resolution of ~15 km s-1. These transitions cover a broad range of temperatures, ionization states, and abundances. The species included are O VI, which probes hot (T ~ 3 × 105 K) ionized gas; C III and Fe III, which probe warm (T ~ 104 K) ionized gas; Si II, P II, C II, Fe II, and O I, which probe warm neutral gas; and six different molecular hydrogen transitions, which trace cold (T ≤ 500 K) gas. We include Schmidt Hα CCD images of the region surrounding each sight line showing the morphology of warm ionized gas in the vicinity, along with continuum images near each FUSE aperture position. We present several initial scientific results derived from this dataset on the interstellar medium of the Magellanic Clouds and Galactic halo. O VI absorption at Magellanic Cloud velocities appears along nearly all sight lines, regardless of optical emission-line morphology. The velocity field of LMC disk material is probed using P II λ1152.8 absorption and is seen to be consistent with recent H I results. While the velocity structure of the SMC is complex, two absorption features are clearly separated in the SMC data—a strong absorption complex between +100 and +130 km s-1, and a weaker feature near +180 km s-1. The velocity separation between these complexes varies with position, being greater on average in the southwest portion of the SMC. A lower velocity absorption component seen the nine sight lines toward the bright H II region N66 in the SMC may be the result of an outflow or an old SNR within this nebular complex. Absorption in Fe II and O I at ~+60 km s-1 and ~+120 km s-1 appear along many LMC sight lines. They are attributed, respectively, to an intermediate-velocity cloud and a high-velocity cloud in the Milky Way halo. Both features are dramatically stronger toward the eastern half of the LMC and are not correlated with each other or with LMC Hα morphology. The lower velocity of the SMC and broader absorption lines complicate the detection of intermediate and high velocity Galactic absorption along SMC sight lines.
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