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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…
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…
Neutral hydrogen in Herbig AE stars.
Catala, C.; Czarny, J.; Felenbok, P. +1 more
The authors have observed a sample of Herbig pre-main sequence stars in the near IR O I lines in view of studying the formation mechanisms of these lines and of comparing them to the O I UV resonance triplet at 1304 Å. The observations consist of high resolution (λ/Δλ = 4×104) spectra of the regions 7773 Å and 8446 Å in seven Herbig Ae …
Discovery of a 9.5-year period in the symbiotic star V1016 Cyg.
Nussbaumer, H.; Schmid, H. M.
Near-infrared observations show that the symbiotic star V1016 Cyg contains a periodicity of 450 days. From ultraviolet observations (IUE) the authors now find a period of 9.5 years. They suggest that V1016 Cyg is a double star system with an orbital period of ≈9.5 years containing a Mira variable. The nature of the source of the hot ionizing radia…
Markarian 52 : a gas-rich starburst galaxy.
Durret, F.; Tarrab, I.
We have observed the "starburst" galaxy Markarian 52(= NGC 4385) both through broad and narrow band imaging, and spectroscopically in the UV and optical ranges. The narrow band Hα+[N II] continuum-free image shows that the ionized gas extends over at least 19" (4.1 kpc). However, our long slit spectroscopic data reveals a much larger extent of the…
Line variations in the ultra-violet spectrum of the Ap-Si star HD 25823.
Artru, M. -C.; Freire-Ferrero, R.
Spectral variations of the Ap-Si star HD 25823 are investigated in the UV range 1250-1900 A, from a set of five IUE images recorded during one rotational period. It is found that line intensities, as well as other wide absorption features, vary versus the phase (up to 20 percent) with different behaviors related to the absorbing elements. The equi…
An active hemisphere on II Peg.
Doyle, J. G.
IUE observations of the RS CVn star II Peg in the upper chromospheric and transition regions lines Mg II k, C IV, and He II in 1981, 1983 and 1985 shows evidence for increased activity at certain phases. The Mg II k line flux shows an above average value between phases 0.0 and 0.5. This is largely biased by the 1981 and 1983 data-sets, although th…
EXOSAT observations of the southern cluster of galaxies S 2008-569.
Piro, L.; Fusco-Femiano, R.
We present the X-ray spectrum of the source 3A 2008-568, associated with the southern cluster of galaxies S 2008-569, obtained with the ME detectors aboard the EXOSAT satellite. The flux was detected in a quadrant pointing in offset position to monitor the background during an observation of another target. An average intracluster gas temperature …
Scattered light between 2 and 13 arcmin from dzeta Orionis in the 1200 to 3000 A wavelength range.
de Boer, K. S.; Kuss, C.
The nature of the spatial enhancement in the scattered intensity in the satellite UV near ζ Ori is investigated. After correction for the scattering contributed by the IUE telescope, the normalised dust-scattered intensity near ζ Ori indicates the presence of small patches of dust very close to ζ Ori inside the larger diffuse shell of Barnard's Lo…
Discrete absorption components : a study of the gas parcel model using component velocity observations.
Bates, B.; Catney, M. G.; Halliwell, D. R.
Available IUE spectra for Beta Ori are used to test the model (Underhill and Fahey, 1984) of the release of discrete parcels of gas from above the stellar photosphere as a possible origin for the discrete absorption components noted in UV spectra. The applicability of late-B supergiants to the present parcel model is questioned. It is suggested th…