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Ulysses observations of Alfvén waves in the southern and northern solar hemispheres
Balogh, A.; Smith, E. J.; Neugebauer, M. +1 more
Alfvén waves with periods from <1 to >10 hours are shown to be continuously present in the sun's south and north polar regions. Below ≈ 30° latitude, as revealed by the rapid traversal of the equatorial region by Ulysses, the wave power averaged over a solar rotation decreases abruptly. The correlations between magnetic field and solar wind …
HST/FOS Spectroscopy of ETA Carinae: The Star Itself, and Ejecta Within 0.3 Arcsec
Walborn, Nolan R.; Weigelt, Gerd; Humphreys, Roberta M. +4 more
Ground-based spectroscopy of η Car includes at least four components ABCD within a core region less than 0.4 across, and usually other material as well. Using the Hubble Space Telescope (HSTs) Faint Object Spectrograph (FOS), we have obtained separate data on component A and on B+C+D. Object A is found to be the central star; this is the fist time…
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, …