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The Ulysses encounter with Jupiter: an introduction
Smith, Edward J.; Wenzel, Klaus-Peter
Goddard High-Resolution Spectrograph Observations of Narrow Discrete Stellar Wind Absorption Features in the Ultraviolet Spectrum of the O7.5 III Star XI Persei
Ebbets, Dennis C.; Bolton, C. T.; Shore, Steven N. +2 more
We report the observation of transient narrow absorption components (NACs) in the stellar wind of the O giant Xi Per. Two sets of GHRS observations of the Si IV ultraviolet resonance doublet have been obtained. These features are extremely weak, with column densities of approximately 10 exp 12/sq cm and optical depths of order 0.1. The features ar…
The star-formation history of GR8 with HST imagery.
Dufour, R. J.; Wyatt, R. J.
The authors report the results of a deep imaging study of the nearby irregular galaxy GR8 using the Wide-Field Camera on the Hubble Space Telescope. These data enable them to perform photometry on stars as faint as R ≡ 24.5 with spatial resolution superior to ground-based observations. Color-magnitude diagrams in the "BVR" filters are presented an…
Structure, motion, and composition of the Orion Nebula.
O'Dell, C. R.
The author reviews the large scale structure of the Orion Nebula, incorporating recent results from 21 cm absorption studies, optical emission line investigations, and Hubble Space Telescope imaging. The ionization structure at the brightest ionization front is clearly defined and demonstrates a well organized flow away from the front. The ionized…
Are PSR 0656+14, PSR 0950+08, and PSR 1822-09 gamma-ray pulsars?
Brown, Lawrence E.; Hartmann, Dieter H.
The possible discovery of three new γ-ray pulsars PSR 0656+14, PSR 0950+08, and PSR 1822-09 (Ma, Lu, Yu, and Young, 1993) in data obtained with the COS-B experiment is reinvestigated using a refined technique for pulsar light curve analysis. The results of this study do not confirm the previously claimed γ-ray pulsar nature of any of these pulsars…
Effect of interstellar absorption on the MG II H & K profiles and fluxes of RS CVn stars
Doyle, J. G.; Houdebine, E. R.; Butler, C. J.
Simulated imaging of the upper atmosphere of active stars
Donati, J. -F.; Catala, C.
We have applied the principles of indirect stellar surface imaging (Doppler imaging) for simulated mapping of active regions in the upper atmosphere of cool active stars. Our tests illustrate how synthetic distributions at the chromosphere or transition region level can be recovered from time series of high resolution profiles of UV lines, as sate…
X-Ray Ultraviolet and Far Infrared Emission of Seyfert Galaxies
Mas-Hesse, J. M.; Rodriguez-Pascual, P. M.; Mirabel, I. F. +3 more
We have compiled multiwavelength data (in the radio, FIR, optical, UV and X-ray ranges) for a sample of 126 galaxies, including QSO, Seyfert 1, Seyfert 2 and galaxies dominated by star-forming processes. We have tested the implications of "unified Seyfert models", which assume that Seyfert 1 and 2 galaxies are intrinsically the same kind of object…
IUE Observations of Highly Ionized Gas toward Distant Stars in the Milky Way
Sembach, Kenneth R.
Combined high-dispersion IUE spectra of interstellar Si IV, C, IV, and N V absorption along distnat lines toward early type stars in the Galactic disk and low halo are discussed. The highly ionized species have complex profiles and exhibit stronger absorption toward distant low latitude stars than toward high latitude stars. Absorption along low l…
The presence of fe VII and of low-ionization features in the UV spectra of central stars of planetary nebulae.
Tweedy, R. W.
The correlation between the presence of N I and Fe VII absorption lines in the spectra of central stars of planetary nebulae reported by Feibelman & Bruhweiler (1990) and Cheng et al. (1991) is refuted. Many spectra that they discuss are severely underexposed; moreover, 12 of them reveal no continuum whatsoever. These therefore cannot be used …