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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 …
Giotto's Mission to planet Earth
Glassmeier, K. -H.; Neubauer, F. M.; Ungstrup, E. +9 more
After its successful encounter with comet P/Halley and a four-years hibernation period ESA's Giotto spacecraft has been reactivated in February 1990 and performed the first-ever Earth gravity-assisted maneuver on July 2, 1990 to be retargeted for comet P/Grigg-Skjellerup. This swing-by is of unique scientific interest due to Giotto's hyperbolic, h…
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…
Time-resolved ultraviolet spectroscopy of the cataclysmic variable PG 1711+336.
Prinja, R. K.; Rosen, S. R.; Supelli, K.
Low-resolution IUE ultraviolet observations of the cataclysmic variable, PG 1711 + 336, are presented. The spectra reveal extensive variability in the wind-formed C IV 1550 A resonance line P Cygni profiles, on time-scales as short as several hours. The high-resolution IUE spectrum of the nova-like system V3885 Sgr, convolved with the IUE low-reso…
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…
Stellar Lyman-Alpha Emission and the Local Interstellar Medium
Simon, Theodore; Landsman, Wayne
The UV spectra now available in the IUE archives have been systematically searched for the presence of Lyman-alpha emission in late-type stars. The results provide the first survey of the behavior of the Ly-alpha emission line across most of the cool half of the H-R diagram. The normalized Ly-alpha emission flux is strongest in the chromospherical…
IUE and TIRGO observations of the symbiotic star HBV 475.
Vogel, M.; Nussbaumer, H.
IUE has observed the symbiotic star HBV 475 since 1979, and the TIRGO long-term IR survey has done so since 1986. The star displays a strikingly regular periodic variation in the fluxes of the emission lines and of their wavelength positions. Observational results are presented in conjunction with an outline of the spectroscopic evolution of this …