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The Hubble Space Telescope Quasar Absorption Line Key Project. I. First Observational Results, Including Lyman-Alpha and Lyman-Limit Systems
Turnshek, David A.; Schneider, Donald P.; Savage, Blair D. +9 more
We present spectra for a total of 37 quasars with small and moderate redshifts; the quasars were observed with the Faint Object Spectrograph of the Hubble Space Telescope. The spectra are obtained either at a resolution of R = 1300 (hereafter "higher resolution") or a resolution of r = 180 (hereafter "lower resolution"). We report new higher resol…
Mechanism for the acceleration and ejection of dust grains from Jupiter's magnetosphere
Horanyi, M.; Grun, E.; Morfill, G.
PERHAPS the most unexpected finding of the Ulysses mission so far has been the detection of quasi-periodic streams of high-velocity, submicrometre-sized dust particles during the spacecraft's encounter with Jupiter1. The impact geometry clearly shows that these small grains originate in the jovian system, but it is surprising that any d…
Early-Type Galaxies, Dark Halos, and Gravitational Lensing Statistics
Maoz, Dan; Rix, Hans-Walter
We present calculations of the expected statistics of gravitational lensing of quasars in the Hubble Space Telescope snapshot survey. We first model early-type (elliptical and SO) galaxies using their observed surface brightness profiles and dynamically inferred mass-to-light ratios. Our work improves upon previous calculations, which have general…
Composition of Interstellar Clouds in the Disk and Halo. I. HD 93521
Fitzpatrick, Edward L.; Spitzer, Lyman, Jr.
Interstellar column densities of Fe, S, Si, Mn, and Mg in their dominant ionization state, as well as of C(+) and S(2+), are presently derived from analyses of HST UV observations of the Galactic halo star HD 93521. Ratios of column densities for the dominant species yield approximations of the logarithmic depletion D(X) in the warm, primarily neu…
Planetary Camera Observations of the Double Nucleus of M31
Holtzman, J. A.; Faber, S. M.; Ewald, S. P. +13 more
V- and I-band HST Planetary Camera images of the great spiral galaxy in Andromeda, M31, show that its inner nucleus consists of two components separated by 0.49". The outer isophotes of the nucleus at 1.4" < r < 3.0" are elongated, but are concentric with the M31 bulge. The nuclear component with the lower surface brightness, P2, is also coi…
Elemental abundances in normal late-B and HgMn stars from co-added IUE spectra. I. Iron-peak elements.
Dworetsky, M. M.; Smith, K. C.
The abundances of five iron-peak elements (chromium through nickel) in a sample of forty normal, superficially normal, and HgMn-type late-B stars are derived by spectrum-synthesis analysis of co-added high-resolution International Ultraviolet Explorer (IUE) spectra. Approximately solar abundances of these elements are obtained for the normal stars…
The Ulysses neutral gas experiment: Determination of the velocity and temperature of the interstellar neutral helium
Rosenbauer, H.; Witte, M.; Banaszkiewicz, M. +1 more
A new technique to directly detect low energy neutral helium has been developed and successfully used in space for the first time. It makes possible the in-situ measurement of the local angular distribution of the flow of interstellar neutral helium in the inner heliosphere. Based on the transformation of a velocity distribution, using Liouville's…
SN 1992A: Ultraviolet and Optical Studies Based on HST, IUE, and CTIO Observations
Suntzeff, N. B.; Fransson, Claes; Challis, Peter M. +18 more
The Type Ia supernova SN 1992A in the 50 galaxy NGC 1380 was observed as a target of opportunity by the International Ultraviolet Explorer (IUE) and with great alacrity by the Hubble Space Telescope (HST). Here we present the HST and lUE spectra and photometry that we obtained, as well as optical spectra obtained at the Cerro Tololo Inter-American…
X-Ray Variability of Active Galactic Nuclei: A Universal Power Spectrum with Luminosity-dependent Amplitude
Papadakis, I.; Lawrence, A.
We present power-law model fits to the power spectra of 12 high- quality "long look" observations of AGNs from the EXOSAT data base. The AGNs concerned differ in X-ray luminosity L_x_, over a range 10^4^. The results are consistent with all objects having a power spectrum index equal to the mean value α = 1.55. There is no correlation with L_x_, s…
Five populations of interplanetary meteoroids
Divine, Neil
A description of the interplanetary meteoroid environment is proposed in terms of distinct populations, each of which has separable distributions in particle mass and in orbital inclination, eccentricity, and perihelion distance. This treatment leads to expressions for particle concentration and flux which explicitly incorporate both Keplerian dyn…