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HD 115781 and HD 116204—two RS CVn binaries
Fekel, Francis C.; Griffin, R. F.
HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined; the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error. There is substantial photometric variability with a period ha…
Electron densities in late-type stars.
Dufton, P. L.; Lennon, D. J.; Byrne, P. B. +2 more
Recently published atomic calculations for the C II UV 0.01 intersystem multiplet at 2325 Å are combined with dearchived IUE data on a number of late-type giants and supergiants to derive the electron densities in these stars' upper chromospheres/lower transition regions. The results represent a substantial change from previously derived values. T…
Effective temperatures and radii of Small Magellanic Cloud supergiants.
Nandy, K.; Houziaux, L.; Thompson, G. I. +1 more
The effective temperatures and radii of Small Magellanic Cloud supergiants are found by comparison with models. The methods used parallel those used previously by ourselves for the Large Cloud and by Underhill and co-workers for the Galaxy. No significant difference is found among these galaxies in this respect. A new analysis of the SMC extinctio…
IUE Observations of X-Ray Selected Stars
Stocke, John; Bergoffen, Martin J.; Walter, Frederick +1 more
UV spectra for four X-ray-selected bright (V less than 10) late-type (F and G) stars have been obtained in both the long- and short-wavelength cameras of the IUE satellite. The stars were selected because they had the largest ratios of X-ray to optical luminosity for their spectral type, with known binaries being eliminated from the sample in orde…
Mass loss and C IV ionization in the stellar wind of OB stars.
Blomme, R.; van Rensbergen, W.
A sample of 19 stars is presented for which both IR and UV observations are available. From the IR, the mass loss rate M can be determined, but it depends on the velocity law in the stellar wind, which is parameterized by the parameter beta(IR). This dependence on beta turns out to be similar for all stars. From the UV, one finds the mass loss rat…
Ultraviolet Spectroscopy of the ``Jetlike'' Condensations of NGC 4151
Bruhweiler, F. C.; Smith, Andrew M.
The spectrometers aboard the International Ultraviolet Explorer (IUE) are used to obtain UV spectroscopy of the jetlike condensations seen extending 18" from the nucleus of the nearby Seyfert 1 galaxy NGC 4151. New data reduction techniques are used to detect, delineate, and measure weak nebular emission in IUE spectra. Spatially resolved extended…
Abundances of Mercury in Sirius and VEGA
Sadakane, Kozo; Takada-Hidai, Masahide; Jugaku, Jun
The resonance line of Hg II at 1942 Å in Sirius and Vega is analyzed quantitatively based on high-resolution UV spectroscopic data. The spectrum synthesis technique is employed. The abundance of Hg in Sirius (log ɛ(Hg) = 2.5±0.5) is found to coincide with that found in the two normal late B-type stars ν Cap and π Cet. On the other hand, the obtain…
Collisions with cometary dust recorded by the Giotto HMC camera.
Keller, H. U.; Curdt, W.
The authors concentrate on the detailed directional information provided by the Halley Multicolour Camera (HMC) as a result of its excellent resolution and the high attitude stability of the Giotto spacecraft. This information was used to determine the trajectory and to identify attitude excursions caused by discrete dust impacts on the space prob…
Voyager and IUE Observations of 3C 273: Detection of Possible Lyman Continuum Absorption in a Nearby (z = 0.158) Quasar
Reichert, G. A.; Carone, T. E.; Wu, C. -C. +1 more
We report results of near-simultaneous IUE and Voyager ultraviolet spectrometer (UVS) observations of 3C 273, obtained during the period of 1985 late July-early August. The data cover a total combined wavelength range 500-3200 A (observed frame). This is the first time that observations shortward of 1200 A have been obtained for any extragalactic …
Position of comet P/Halley at the Giotto encounter
Wilhelm, K.; Keller, H. U.; Curdt, W. +2 more
Images of the Halley Multicolor Camera (HMC) were analyzed to evaluate the fly-by geometry of the Giotto spacecraft past Comet Halley. The position of the comet at closest approach was determined with respect to the spacecraft. Based on the orbit information of Giotto the absolute position of the cometary nucleus could be obtained with very high p…