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IUE Observations of Early-Type Stars at High Galactic Latitudes
Dufton, P. L.; Keenan, F. P.; Brown, P. J. F. +2 more
High- and low-resolution IUE spectra of 14 apparently normal high-Galactic latitude B-type stars, together with visual fluxes determined from Stroemgren four-color photometry, are compared with theoretical spectra deduced from LTE model atmosphere calculations. Ten of the program stars have normal flux distributions, with only four of the stars ex…
A Non--Local Thermodynamic Equilibrium, Line-blanketed Synthetic Spectrum of IOTA Herculis: C, Al, and SI Lines
Grigsby, James A.
A non-LTE line-blanketed model stellar atmosphere is used to compute a model of I Herculis (B3 IV) with a Teff of 17,500 K and a log g of 3.75, following the conclusions of Peters and Polidan (1985). Detailed profiles of a number of lines of C, Al, and Si in the 1200-2000-A region are computed, including the resonance lines of C II, Al II, and Al …
First Results from the Faint Object Camera: High-Resolution Imaging of the Pluto-Charon System
Boksenberg, A.; Barbieri, C.; Weigelt, G. +16 more
The first observations of a solar system target with the Faint Object Camera of the HST are reported. Observations of the Pluto-Charon system were obtained in f/96 and f/288 mode. Pluto and Charon were clearly resolved, and the observed separation and diameters are in accordance with expectations. The f/96 data were astrometrically and photometric…
First Results from the Goddard High-Resolution Spectrograph: A Demonstration of Spectral Resolution and Experiments with Deconvolution
Ebbets, Dennis C.; Shore, Steven N.; Gilliland, Ronald L. +3 more
High-quality spectra of the sharp-lined star Chi Lupi were obtained with the Goddard High Resolution Spectrograph (GHRS). Spectra for the various resolving powers achievable with the echelle and G160M gratings are displayed. The effect of spherical aberration upon the spectral resolution is found to be negligible when using the small science apert…
X-Ray to Infrared Observations of the AM Herculis System E1405-451 (V834 Centauri)
Maraschi, L.; Chiappetti, L.; Motch, C. +5 more
The Exosat satellite observed E1405 - 451 in the X-ray band in March 1984 during a high state; and simultaneous UV, optical, and IR coverage was obtained with IUE and from ESO telescopes. The low-energy X-ray curve exhibits a minimum at phase zero which is similar to the optical one, with some indication of temperature modulation with orbital phas…
On Spectra of X-Ray Bursters in the Expansion Phase
Lapidus, I. I.
Two alternative approaches to the theoretical description of spectra of X-ray bursters showing radial expansion near the light curve maximum are presented. The first one, using the LTE assumption, can be used to explain the noticeable soft excess which is present in corresponding Exosat observations. The second one is based on numerical calculatio…
C IV Line Profile Correlations in NGC 4151
Michalitsianos, A. G.; Kazanas, D.; Fahey, R. P.
The core of the strong UV resonance line C IV in the Seyfert 1 galaxy NGC 4151 is characterized by a double-peaked profile whose narrow emission features have relative intensities that vary as a function of the total C IV line strength. We present herein a set of novel correlations between the peak emission of each of these two components and the …
Wind Collision Effects in the Early-Type Close Binaries HD 47129 and AO Cassiopeiae
Sahade, Jorge; Brandi, Estela
Selected regions of IUE spectra of the binaries HD 47129 and AO Cassiopeiae are analyzed, and evidence for the effect of wind collision in both objects is found. A possible alternative explanation for the behavior of the spectral lines of the 'secondary' component in HD 47129 is suggested.
IUE Observations of Solar-Type Stars in the Pleiades and the Hyades
Linsky, Jeffrey L.; Vilhu, Osmi; Caillault, Jean-Pierre
An extensive set of IUE observations of solar-type stars (spectral types F5-G5) in the Pleiades is presented. Spectra were obtained in January and August 1988 for both the transition region and chromospheric emission wavelength regions, respectively. Mg II fluxes were detected for two out of three Pleiades stars and C IV upper limits for two of th…
Inference of the Extreme-Ultraviolet Continuum Shape of Quasars
Zheng, Wei
The strength of C IV emission in weak-bump QSOs is significantly larger than that in strong-bump QSOs. Equivalent widths of Lyα, Si IV, and C III show no sign of difference between objects with various UV bump strength. The finding suggests that the "big UV bump" is a source of ionization and can be scaled by emission lines. The higher average C I…