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Correspondence between field aligned currents observed by Ulysses and HST auroral emission
Dougherty, M. K.; Dunlop, M. W.; Prange, R. +1 more
Auroral emission is direct evidence for the magnetophere/ionosphere coupling which exists for a magnetised planet such as Jupiter. This coupling takes place by way of momentum transfer which occurs via field aligned currents. The driving mechanism for the auroral emission is charged particle precipitation along the field lines. During the Ulysses …
The STIS Parallel Survey: Introduction and First Results
Ferguson, Henry C.; Baum, Stefi A.; Gardner, Jonathan P. +15 more
The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS) routinely obtains broadband images and slitless spectra of random fields in parallel with HST obs…
Elemental Abundances in Coronal Structures
Kohl, John L.; Noci, Giancarlo; Raymond, John C. +1 more
A great deal of evidence for elemental abundance variations among different structures in the solar corona has accumulated over the years. Many of the observations show changes in the relative abundances of high- and low-First Ionization Potential elements, but relatively few show the absolute elemental abundances. Recent observations from the SOH…
A Long-Period Spectroscopic Binary in the O-Star Multiple System HD 193322
Bolton, C. T.; Fullerton, A. W.; Gies, D. R. +8 more
We present radial velocity measurements and a single-lined spectroscopic orbit for the bright O-type star, HD 193322A, which we show to be a 311 day binary system that has a distant third companion (detected by speckle interferometry) in a 31 yr orbit. We suggest that the speckle companion appears in the spectrum as a broad-lined component of earl…
Evolution of the near-infrared in rich galaxy clusters
Mobasher, Bahram; Trentham, Neil
We present the K-band (2.2 µm) luminosity functions (LFs) of the X-ray-luminous clusters MS1054-0321 (z=0.823), MS0451-0305 (z=0.55), Abell 963 (z=0.206), Abell 665 (z=0.182) and Abell 1795 (z=0.063) down to absolute magnitudes M_K=-20. Our measurements probe fainter absolute magnitudes than do any previous studies of the near-infrared LFs o…
Deep Hubble Space Telescope Galaxy and Pair Counts as Tests of Merger History
Keel, William C.; Wu, Wentao
We consider the use of counts of faint galaxy pairs as tests of the role of merging in galaxy evolution, using both simulations and Hubble Space Telescope (HST) data in comparison with models incorporating a range in the evolution of merger rate. Artificial data, including simulation of the surface-brightness selection effects implicit in HST imag…
Mid-IR mapping of the region of N 4 in the Large Magellanic Cloud with ISOCAM
Boulanger, F.; Heydari-Malayeri, M.; Sauvage, M. +9 more
We present images of the N 4 region in the Large Magellanic Cloud obtained with ISOCAM on board ISO through broad band filters centered at 6.75 and 15 mu m. Far from the three H i I regions contained in the map, the emission at both wavelengths is due to the Unidentified Infrared Bands and associated continuum and originates in the external layers…
Stellar Populations and Variable Stars in the Core of the Globular Cluster M5
Drissen, Laurent; Shara, Michael M.
We report the discovery of a variable blue straggler in the core of the globular cluster M5, based on a 12 hr-long series of images obtained with the Planetary Camera aboard the Hubble Space Telescope. In addition, we present the light curves of 28 previously unknown or poorly studied large-amplitude variable stars (all but one are RR Lyrae stars)…
An alternative explanation of the EUV spectrum of the white dwarf G191-B2B invoking a stratified H+He envelope including heavier elements
Barstow, M. A.; Hubeny, I.
Only recently has it been possible to find an effective temperature and composition for the hot DA white dwarf G191-B2B which can consistently match the optical, far-UV and EUV data simultaneously, by using new non-LTE model calculations that include the effects of line blanketing from more than 9 million (mainly Fe and Ni) transitions. However, t…
Dark haloes of spiral galaxies: ISO photometry
Gilmore, Gerard; Unavane, M.
We exclude hydrogen-burning stars, of any mass above the hydrogen-burning limit and any metallicity, as significant contributors to the massive haloes deduced from rotation curves to dominate the outer parts of spiral galaxies. We present and analyse images of four nearly edge-on bulgeless spiral galaxies (UGC 711, NGC 2915, UGC 12426, UGC 1459) o…