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HIPPARCOS link with Carte du Ciel triple images.
Tucholke, H. -J.; Brosche, P.; Guibert, J. +3 more
This study for the first time investigates the possibility of deriving astrometric positions for bright stars on Carte du Ciel (CdC) plates, whose triple images are not separable. The field from the Bonn Hipparcos Extragalactic Link Programme with the BL Lac object OJ 287 has been selected. The triple images on the CdC plate were modelled by three…
IUE observations of X-ray nova MUSCAE 1991 during outburst.
Shrader, C. R.; Gonzalez-Riestra, R.
We report on a series of ultraviolet spectroscopic observations made with the lUE satellite, which sampled critical outburst stages of the soft X-ray transient Nova Muscae 1991. Continuum light curves, and multi-epoch line analysis are presented. The λλ1500-3300 continuum fits approximately the "canonical" fv∝ν1/3 power law e…
Extended Variability of the Symbiotic Star AG Draconis
Kafatos, M.; Meier, S. R.; Martin, I.
High and low resolution IUE satellite observations of the symbiotic star AG Draconis covering the period 1979-1989 are presented, and the far-UV spectra are studied. Two extended outburst events are found to have two maxima separated by about 1600 days, a time scale not known to be associated with the star but which is about three times the binary…
Winds in Central Stars of Planetary Nebulae
Modigliani, A.; Patriarchi, P.; Perinotto, M.
We studied five central stars of planetary nebulae with IUE high-resolution spectra to determine the wind properties of their central stars. Using the best stellar and nebular parameters, and analyzing the P Cygni profiles seen in lines of the ions C IV, N V, N IV, O V, O IV, and Si IV with the SEI method, we have obtained the following values of …
Studies of narrow polar rings around E galaxies. II. The UV spectrum of AM 2020-504.
Buson, Lucio; Arnaboldi, Magda; Longo, Giuseppe +2 more
Four ultraviolet (UV) full-shift spectra secured with the IUE satellite have been used to test the accretion scenario for the still unexplored class of the "narrow" polar ring (PR) galaxies. The UV energy distribution in the λλ 1200 - 3300 A range for the "prototype" of this class, the system AM 2020-504, is found to be different from the UV emiss…
The structure of Jupiter's Io plasma torus inferred from Ulysses radio occultation observations
Pätzold, M.; Bird, M. K.; Asmar, S. W. +3 more
The radio downlinks from Ulysses were monitored during the passage of the spacecraft through the Io plasma torus shortly after closest approach to Jupiter. The electron content of the Io torus was derived from the dispersive phase shift of the S-band (2.3 GHz) signal with respect to the X-band (8.4 GHz) signal. Corrections were applied for non-Jov…
Particle Drifts for a Finite Scattering Rate
Jokipii, J. R.
The Hydrogen Lyman-Alpha Emission of Capella
Ayres, Thomas R.; Linsky, Jeffrey L.; Gayley, K. G. +1 more
We describe the hydrogen Ly-alpha emission of the spectroscopic binary Capella (G8 III + GO III) recorded at 0.1 A resolution by the International Ultraviolet Explorer. The overt changes in the composite line shape with orbital phase are controlled by the active GO III star and permit a dissection of the stellar components despite the obliteration…
Low-resolution spectra of the Io plasma torus 2 days after the Ulysses encounter
Rauer, H.; Thomas, N.; Jockers, K. +1 more
Low-resolution spectra of the Io plasma torus have been obtained on 10 and 11 February 1992 (2 days after the Ulysses encounter) using the 2 m telescope of the Bulgarian National Observatory. The spectra show the forbidden line emissions of S + (λλ 6716, 6731 Å) and S 2+ (λ 6312 Å). Measured intensities are compared with a Vo…
X-Ray Light Curves of Active Galactic Nuclei Are Phase Incoherent
Done, Chris; Krolik, Julian; Madejski, Grzegorz
We compute the Fourier phase spectra for the light curves of five low- luminosity active galactic nuclei observed by EXOSAT. There is no statistically significant phase coherence in any of them. This statement is equivalent, subject to a technical caveat, to a demonstration that their fluctuation statistics are Gaussian. Models in which the X-ray …