Interstellar O VI in the Large Magellanic Cloud

Abstract

I summarize Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar O VI absorption towards 12 early-type stars in the Large Magellanic Cloud (LMC), the closest disk galaxy to the Milky Way. LMC O VI is seen towards all 12 stars with properties (average column densities, kinematics) very similar to those of the Milky Way halo, even though O/H in the LMC is lower by a factor of ~2.5. Sight lines projected onto known LMC superbubbles show little enhancement in O VI column density compared to sight lines towards quiescent regions of the LMC. The O VI absorption is displaced by \~-30 km/sec from the corresponding low-ionization absorption associated with the bulk of the LMC gas. The LMC O VI most likely arises in a vertically-extended distribution, and I discuss the measurements in the context of a halo composed of radiatively-cooling hot gas. In this case, the mass-flow rate from one side of the LMC disk is of the order 1 solar mass/yr.