Bart P. Wakker

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We report the results of a F U SE study of high velocity O VI absorption along complete sight lines through the Galactic halo in directions toward 100 extragalactic objects and 2 halo stars. The high velocity O VI traces a variety of phenomena, including tidal interactions with the Magellanic Clouds, accretion of gas, outflowing material from the Galactic(More)
We present a study of the Lyα forest at z 0.4 from which we conclude that at least 20% of the total baryons in the universe are located in the highly-ionized gas traced by broad Lyα absorbers. The cool photoionized low-z intergalactic medium (IGM) probed by narrow Lyα absorbers contains about 30% of the baryons. We further find that the ratio of broad to(More)
We estimate the abundances of S and Fe in the high velocity cloud HVC 287.5+22.5+240, which has a velocity of +240 km s −1 with respect to the local standard of rest and is in the Galactic direction l ∼ 287 0 and b ∼ 23 0. The measurements are based on UV absorption lines of these elements in the Hubble Space Telescope spectrum of NGC 3783, a background(More)
We have conducted a study with the VLA, the DRAO ST, and the FUSE satellite to search for the intra-group medium in two loose groups of galaxies: GH 144 and GH 158. The VLA observations provide a census of the dense H I content of these groups in the form of individual galaxies and free-floating H I clouds as traced by the 21-cm H I line, while the FUSE(More)
Models of the chemical evolution of the Milky Way suggest that the observed abundances of elements heavier than helium ('metals') require a continuous infall of gas with metallicity (metal abundance) about 0.1 times the solar value. An infall rate integrated over the entire disk of the Milky Way of approximately 1 solar mass per year can solve the 'G-dwarf(More)
Using Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) observations of the QSO PG 1259+593, we detect D I Lyman-series absorption in high velocity cloud Complex C, a low-metallicity gas cloud falling onto the Milky Way. This is the first detection of atomic deuterium in the local universe in a location other than the nearby(More)
The large H ii complex N11 in the Large Magellanic Cloud contains OB associations at several different stages in their life histories. We have obtained ROSAT PSPC and HRI X-ray observations, Curtis Schmidt CCD images, echelle spectra in Hα and [N II] lines, and IUE interstellar absorption line observations of this region. The central bubble of N11 has an(More)
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar molecular hydrogen (H 2) in two Galactic high-velocity clouds (HVCs). Molecular hydrogen absorption is detected in the Magellanic Stream (abundance ∼ 0.3 solar) toward the Seyfert galaxy Fairall 9 in the lowest three rotational states (J = 0 − 2) at v LSR = +190 km s −1 ,(More)