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Interacting elliptical galaxies as hosts of intermediate-redshift quasars
Boksenberg, A.; Crane, P.; Sparks, W. B. +7 more
QUASARS are the most luminous objects in the Universe. It has been speculated that they are the visible evidence for accretion of gas onto supermassive black holes that reside at the centres of host galaxies. Direct observational confirmation that quasars reside in the centres of galaxies has been hard to obtain, because atmospheric turbulence usu…
Evolution of Infrared-selected Galaxies in Z approximately 0.4 Clusters
Dickinson, Mark; Stanford, S. A.; Eisenhardt, P. R. M.
Wide-field optical and near-IR (JHK) imaging is presented for two rich galaxy clusters: Abell 370 at z = 0.374 and Abell 851 (Cl 0939+47) at z = 0.407. The new data are combined to produce colors sampling the 0.55-1.65 micron range in the rest frame. Galaxy catalogs selected from the near-IR images are 90% complete to a limiting magnitude approxim…
The DIM Inner Accretion Disk of the Quiescent Black Hole A0620-00
Remillard, Ronald A.; McClintock, Jeffrey E.; Horne, Keith
We observed the X-ray nova A0620-00 with the Hubble Space Telescope (HST) Faint object Spectrograph 16 yr after its 1975 outburst. We present a single spectrum (1250-4750 A), which is approximately an average over a full 7.8 hr orbital cycle of the source. The continuum can be fitted approximately by a blackbody model with T = 9000 K and a small p…
Properties of magnetohydrodynamic turbulence in the solar wind as observed by Ulysses at high heliographic latitudes
Balogh, A.; Horbury, T. S.; Smith, E. J. +3 more
The Ulysses mission provides an opportunity to study the evolution of magnetohydrodynamic (MHD) turbulence in pure high-speed solar wind streams. The absence at high heliocentric latitudes of the strong shears in solar wind velocity generally present near the heliocentric current sheet allows investigation of how fluctuations in the magnetic field…
SWAN: A Study of Solar Wind Anisotropies on SOHO with Lyman Alpha Sky Mapping
Schmidt, W.; Dimarellis, E.; Torsti, J. +22 more
On board the SOHO spacecraft poised at L1 Lagrange point, the SWAN instrument is mainly devoted to the measurement of large scale structures of the solar wind, and in particular the distribution with heliographic latitude of the solar wind mass flux. This is obtained from an intensity map of the sky Lymanα emission, which reflects the shape of the…
The Physics of Massive OB Stars in Different Parent Galaxies. I. Ultraviolet and Optical Spectral Morphology in the Magellanic Clouds
Walborn, Nolan R.; Kudritzki, Rolf-Peter; Lennon, Daniel J. +2 more
HST/FOS and ESO 3.6m/CASPEC observations have been made of 18 stars ranging in spectral type from O3 through B0.5 Ia, half of them in each of the Large and Small Magellanic Clouds, in order to investigate massive stellar winds and evolution as a function of metallicity. The spectroscopic data are initially presented and described here in an atlas …
The Pulsation Index, Effective Temperature, and Thickness of the Hydrogen Layer in the Pulsating DA White Dwarf G117-B15A
Koester, D.; Percival, J. W.; van Citters, G. W. +6 more
We have measured the amplitude of the 215 s pulsation of the pulsating DA white dwarf, or ZZ Ceti star, G117-B15A in six passbands with effective wavelengths from 1570 to 6730 A. We find that the index of the pulsation is l = 1 with a high degree of confidence, the first unambiguous determination of l for a pulsation of a ZZ Ceti star. We also fin…
HST Spectroscopic Observations of Jupiter After the Collision of Comet Shoemaker-Levy 9
Atreya, S. K.; Trafton, L. M.; Caldwell, J. J. +6 more
Ultraviolet spectra obtained with the Hubble Space Telescope identified at least 10 molecules and atoms in the perturbed stratosphere near the G impact site, most never before observed in Jupiter. The large mass of sulfur-containing material, more than 1014 grams in S_2 alone, indicates that many of the sulfur-containing molecules S_2, …
Weak pitch angle scattering of few MV rigidity ions from measurements of anisotropies in the distribution function of interstellar pickup H+
Geiss, J.; Schwadron, N. A.; Gloeckler, G. +1 more
The distribution function of interstellar pickup hydrogen is measured with the SWICS instrument on Ulysses at high heliographic latitudes, over a broad range of velocities, including those below that of the solar wind. It is found that these few MV rigidity protons exhibit a pronounced inward radial streaming in the frame of the solar wind, sugges…
The Nature of the Ultraviolet Continuum in Type 2 Seyfert Galaxies
Leitherer, C.; Calzetti, D.; Meurer, G. +6 more
Type 2 Seyfert nuclei are well known to contain a "featureless continuum" which makes a significant contribution in the optical and ultraviolet. However, the nature of this featureless continuum is not clear. Recent optical spectropolarimetry shows that only a minor part of the optical featureless continuum can be light from a hidden Seyfert 1 nuc…