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)
A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder * Hubble Fellow. 2 Dickey et al. telescope. The survey will study the distribution of H i emission and absorption with(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)
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)
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)
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)