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[65.07] FUSE Observations of Degree-Scale Variations in Galactic Halo O VI

J.C. Howk (Johns Hopkins), B.D. Savage (Wisc), K.R. Sembach (STScI), C.G. Hoopes (Johns Hopkins)

We report Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar O VI absorption in the halo of the Milky Way towards 12 early-type stars in the Large Magellanic Cloud (LMC) and 11 in the Small Magellanic Cloud (SMC). The mean column densities of O VI associated with the Galactic halo towards the LMC and SMC are log = 14.52(+0.10,-0.14) and 14.13(+0.14,-0.20), respectively, where the uncertainties represent the standard deviations of the individual measurements about the means. Significant variations in the O VI column densities are observed over all of the angular scales probed by our observations: 0.5 to 5.1 degrees towards the LMC and 0.05 to 3.3 degrees towards the SMC. The maximum factors by which the O VI varies between sight lines towards the LMC and SMC are approximately 2.9 and 4.1, respectively. The column density variations trace the structure of the hot ionized medium in the Galactic halo on scales of <<80 to 800 pc towards the LMC and <<5 to 400 pc towards the SMC (assuming the absorption arises within the first 5 kpc above the Galactic plane).

This work is based on data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission. Financial support has been provided by NASA contract NAS5-32985. JCH and KRS recognize support from NASA Long Term Space Astrophysics grant NAG5-3485.

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